Research Article
Breast Imaging
January 2005

Detection of Breast Cancer on Screening Mammography Allows Patients to Be Treated with Less-Toxic Therapy

Abstract

OBJECTIVE. Therapy for breast cancer is accompanied by acute and chronic toxicity. Little research has been conducted to determine the impact of the mode of breast cancer detection on the likelihood of receiving different types of treatment. The objective of this study was to determine whether detection of breast cancer on screening mammography is associated with less-toxic therapy.
MATERIALS AND METHODS. The study group for this retrospective cohort study consisted of 992 women with invasive breast cancer detected on screening mammography (n = 460) or at physical examination (n = 532) at a single institution between 1990 and 2001. To address the generalizability of study findings, we compared the characteristics of study participants with those diagnosed with breast cancer in a population-based mammography registry.
RESULTS. The patients whose breast cancer was detected on screening mammography more frequently had lymph nodes free of metastases (84% vs 58%, p < 0.0001), had smaller tumors (1.5 vs 2.9 cm, p < 0.0001), were more likely to be treated with breast conservation (56% vs 32%, p < 0.0001), and were less likely to be treated with chemotherapy (28% vs 56%, p < 0.0001). In a multivariate analysis with adjustments for age and functional status, patients whose cancer was detected at physical examination were more than twice as likely to undergo mastectomy (odds ratio [OR], 2.5; 95% confidence interval [CI], 1.9–3.3) and nearly three times as likely to be treated with chemotherapy (OR, 2.9; 95% CI, 2.1–3.9). For younger women (40–49 years old), the likelihood of receiving chemotherapy was more than doubled if the cancer was detected at physical examination rather than on screening mammograms (OR, 2.3; 95% CI, 1.3–4.0). For older women (≥ 70 years old), patients whose cancer was detected at physical examination were five times more likely to undergo mastectomy (OR, 5.8; 95% CI, 3.2–10.5) and four times more likely to receive chemotherapy (OR, 4.6; 95% CI, 1.6–13) than the group whose tumors were detected on screening mammography.
CONCLUSION. Breast cancers detected on screening mammography are smaller, are less likely to metastasize to lymph nodes, and are more likely to be treated with breast conservation and without chemotherapy. These findings provide an additional rationale for performing screening mammography, especially for women at age extremes for whom the survival benefit of screening mammography is debated.

Introduction

The preponderance of evidence from eight randomized controlled trials has led expert panels to conclude that screening mammography reduces mortality from breast cancer [1]. The evidence for a survival benefit from screening mammography is strongest for the 50- to 69-year-old age group. The survival benefit of screening mammography for women 40–49 years old is debated because a study that specifically enrolled women of this age group failed to show a survival benefit [2]. Although the U.S. Preventive Services Task Force, the American Medical Association, and the American Cancer Society recommend screening for this age group, a National Institutes of Health consensus panel, the Canadian Task Force on Preventive Health Care, and the American Academy of Family Physicians recommend that mammographic screening start at age 50 [35]. Furthermore, few data about the survival benefit of screening mammography in women 70 years old and older are available; only one study, the Swedish Two-County Trial [6], included patients in this age group; the eligible patients in that study ranged in age between 40 and 74 years.
In our study, we sought to evaluate the effect of the mode of breast cancer detection on treatment decisions. Breast cancers detected on screening mammography are smaller and more likely not to have spread to the regional lymph nodes when compared with breast cancers detected at physical examination [712]. We hypothesized that patients whose breast cancer is detected on mammography can be treated with less-morbid therapy than patients whose breast cancer is detected at physical examination. The morbidity of treatment includes not only whether patients undergo mastectomy versus breast conservation but also whether patients are treated with chemotherapy.
Adjuvant cytotoxic chemotherapy is recommended commonly to breast cancer patients with lymph node metastases or with tumors greater than 1 cm in diameter, with the exception of the very elderly or those with significant comorbidities [13]. This therapy is associated with several side effects. For example, in one representative cooperative group trial using four cycles of doxorubicin hydrochloride and cyclophosphamide, complications were seen in the following percentages of patients: alopecia, 82%; vomiting, 8%; nausea, 7%; neutropenia, 7%; sepsis, 5%; and severe infection, 4% [14]. More than half of all patients in that study experienced grade 2 or greater toxicity [14]. Furthermore, studies have shown that breast cancer patients undergoing chemotherapy compared with those not treated with chemotherapy are affected by both short- and long-term deficits in memory and learning that are associated with reductions in the quality of life and that persist for as long as 10 years after therapy is completed [15, 16]. Therefore, we undertook a retrospective cohort study to determine whether associations exist between the mode of detection and subsequent treatment.

Materials and Methods

Study Population

After obtaining the approval of our institution's committee for the protection of human subjects, we used the clinical information system at our medical center to identify all women who underwent surgery for invasive breast cancer between January 1, 1990, and December 31, 2001. Women with ductal or lobular carcinoma in situ were excluded from the analysis. For women who had more than one occurrence of invasive breast cancer in the time period of interest, we included only the first occurrence. Once these women were identified, we reviewed their medical records and extracted clinical data using a standardized medical record abstraction form developed for this purpose. The mode of breast cancer detection was classified as screening mammography or physical examination. In patients who detected a sign of breast cancer that was confirmed at physical examination by their physician and patients whose breast cancer was detected first by their physician at physical examination, the mode of detection was considered to be physical examination. The most common sign of breast cancer was a palpable mass, but some patients presented with indentations, nipple retraction, or nipple discharge. Other clinical data included patient age, menopausal status, and Karnofsky (functional health) performance status; tumor size, histologic type, Bloom-Richardson grade, and estrogen receptor status; presence of angiolymphatic invasion; nodal status; and type of treatment received, including type of surgery performed and receipt of adjuvant therapy. Data were entered into a relational database for analysis.
To address the generalizability of study findings given that the study population was ascertained from a single institution, we compared the characteristics of the women in the study population with the characteristics of women in a population-based mammography registry that captures information about more than 90% of women receiving mammography in New Hampshire [17, 18]. Using similar methods to those used in identifying women for analysis in the main study, we identified all cases of invasive breast cancer in the registry for the period of May 1, 1996, to December 31, 2001. We then determined if the cancer was found on screening mammography or at physical examination. A data file was created that included the characteristics of the women from the New Hampshire Mammography Network with the mode of detection as screening mammography or physical examination, which was identified using an indicator variable. A small fraction (≈ 10%) of the patients in the New Hampshire Mammography Network were treated at Dartmouth-Hitchcock Medical Center and therefore also are included in our study group.

Statistical Analysis

Comparisons between groups (detected on screening mammography vs detected at physical examination) were made using chi-square and t tests. To examine the effect of clinical presentation on whether a patient received mastectomy versus lumpectomy and chemotherapy versus no chemotherapy, we used logistic regression and adjusted for patient characteristics (age, menopausal status, and Karnofsky performance status). Analyses were done for the groups overall and were stratified by age group. We compared data on personal and tumor characteristics from this study with data from the New Hampshire Mammography Network using the Mantel-Haenszel test to control for the mode of presentation. Tests were two-sided, and we considered a p value of less than 0.05 to be statistically significant.

Results

Nine hundred ninety-two women with invasive breast cancer were identified by our institution's clinical information system. All had medical records available for extraction. More than 1,600 women (n = 1,614) with invasive breast cancer were identified in the New Hampshire Mammography Registry. Table 1 compares the characteristics of women with invasive breast cancer in the study population with those in the population-based mammography registry. As indicated, no differences were noted in patient age or menopausal status.
TABLE 1 Characteristics of Study Women by Presentation Compared with a Population-Based Sample of New Hampshire Women with Invasive Breast Cancer
CharacteristicPresentation of Study Women (n = 992)Presentation of New Hampshire Women with Breast Cancer (n = 1,614)pa
Physical ExaminationScreening MammographyPhysical ExaminationScreening Mammography
Mean age (yr)566056610.18
Age (yr) by category in decades (%)     
   < 4010.51.511.11.6 
   40-4931.419.828.916.7 
   50-5922.626.521.628.7 
   60-6913.527.616.024.2 
   70-7915.219.816.022.0 
   80+6.84.86.46.8 
% Postmenopausal
61
82
60
79
0.21
a
Using Mantel-Haenszel statistic to compare study women with New Hampshire women
Table 2 compares characteristics of the study group, their tumors, and their treatment as a function of the mode of breast cancer detection. Patients whose cancers were detected on screening mammography were slightly older and were more likely to be postmenopausal than patients whose cancer was detected at physical examination. The functional health status of the women in each group was similar, as indicated by their Karnofsky performance status scores. Tumors detected on screening mammography were only half as large as those detected at physical examination (1.5 vs 2.9 cm, p < 0.0001) and were less likely to be node-positive (16% vs 42%, p < 0.0001). Chemotherapy is not recommended for most patients whose tumors are less than 1 cm in diameter and are node-negative [13]. One third of the mammography-detected cancers fell into this category compared with only 7% of the tumors detected at physical examination.
TABLE 2 Characteristics of Study Women, Their Tumors, and Treatment Received, by Mode of Presentation
CharacteristicPresentation of Study Women
Physical Examination (n = 532)Screening Mammography (n = 460)p
Characteristics of women   
   Mean age (yr)56 (14)60 (12)< 0.0001
   % Postmenopausal6182< 0.0001
   Mean Karnofsky performance status90 (9)89 (8)0.03
Characteristics of tumors   
   % Invasive ductal carcinomaa90940.02
   Mean tumor size (cm)2.9 (2.1)1.5 (1.2)< 0.0001
   Median tumor size (cm)2.21.2 
   % Node positive4216< 0.0001
   % < 1 cm and node negative733< 0.0001
   % Angiolymphatic invasion3817< 0.0001
   % Estrogen receptor positive77850.002
   Mean tumor grade2.3 (0.7)1.9 (0.7)< 0.0001
Characteristics of treatment   
   % Treated with breast conservation3256< 0.0001
   % Treated with chemotherapy5628< 0.0001
   % Treated with tamoxifen
60
57
0.30
Note.-Numbers in parentheses are SDs.
a
Remaining patients had invasive lobular carcinoma. Ductal carcinoma in situ not included in analysis
We observed that patients whose cancers were detected on screening mammography had a lower tumor grade and were less likely to have angiolymphatic invasion (Table 2). In contrast to the marked differences in tumor size and node status, the difference in the percentage of patients whose tumors had increased estrogen receptor was small (85% vs 77%).
Patients whose breast cancer was detected on screening mammography were half as likely to receive chemotherapy as those whose tumors were detected at physical examination (28% vs 56%, p < 0.0001) (Table 2). Furthermore, patients whose cancer was detected on screening mammography were nearly twice as likely to be treated with breast conservation versus mastectomy (56% vs 32%, p < 0.0001). The mode of detection did not affect the likelihood of treatment with tamoxifen.
We also evaluated the subset of 258 patients in the 40- to 49-year-old age group (Table 3). For this group, the tumors detected on mammography were smaller (1.6 vs 2.8 cm, p < 0.0001) and less likely to be node-positive (26% vs 48%, p = 0.001). Whereas only 7% of the 40- to 49-year-old patients with cancer detected at physical examination had tumors that were smaller than 1 cm and node-negative, 33% of those detected on screening mammography fell into this category. The estrogen receptor status of the tumors in each group were similar. As we found with the overall study group, significantly fewer 40- to 49-year-old patients whose breast cancers were detected on mammography were treated with chemotherapy (57% vs 75%, p = 0.003), and more were treated with breast conservation (52% vs 38%, p = 0.03).
TABLE 3 Characteristics of Tumors and Treatment Received in Study Women, by Age and Mode of Presentation
CharacteristicAge 40-49 yrAge 50-69 yrAge ≥ 70 yr
Physical Exam (n = 167)Screening Mammography (n = 91)pPhysical Exam (n = 192)Screening Mammography (n = 249)pPhysical Exam (n = 117)Screening Mammography (n = 113)p
Characteristics of women         
   % Postmenopausal15250.0491960.021001001.0
   Mean Karnofsky performance status94 (8)94 (7)0.6189 (8)89 (7)0.6285 (9)84 (8)0.40
Characteristics of tumors         
   % Invasive ductala carcinoma93950.7386960.00189900.73
   Mean tumor size (cm)2.8 (1.8)1.6 (1.3)< 0.00012.9 (2.2)1.5 (1.2)< 0.00012.9 (2.4)1.4 (1.1)< 0.0001
   % Node positive48260.0014514< 0.000128120.002
   % < 1 cm in size and node negative733< 0.0001732< 0.0001739< 0.0001
   % Angiolymphatic invasion42220.0023618< 0.0001306< 0.0001
   % Estrogen receptor positive77820.4077860.0282890.13
   Mean tumor grade2.3 (0.7)2.0 (0.6)0.022.2 (0.7)1.9 (0.7)< 0.00012.2 (0.6)1.7 (0.6)< 0.0001
Characteristics of treatment         
   % Treated with breast conservation38520.033054< 0.00012766< 0.0001
   % Treated with chemotherapy75570.0035527< 0.00011540.01
   % Treated with tamoxifen
61
52
0.14
61
60
0.73
61
54
0.30
Note.-Numbers in parentheses are SDs.
a
Remaining patients had invasive lobular carcinoma. Ductal carcinoma in situ not included in analysis
We also evaluated women in the older age group (≥ 70 years old), and similar relationships were observed (Table 3). The mean size of the tumors detected on screening mammography was half as large as that of tumors detected by palpation (1.4 vs 2.9 cm, p < 0.0001), and these patients were less than half as likely to be node-positive (12% vs 28%, p = 0.002). Whereas only 7% of the patients 70 years old or older with cancer detected at physical examination had tumors that were smaller than 1 cm and node-negative, 39% of those with cancer detected on screening mammography fell into this group. The estrogen receptor status of the tumors in the two groups was similar. Significantly fewer patients 70 years old or older whose tumors were detected on screening mammography were treated with chemotherapy (4% vs 15%, p = 0.01), and more were treated with breast conservation (66% vs 27%, p < 0.0001).
Because we found differences in the characteristics of the patients whose tumors were detected on screening mammography versus those whose cancers were detected at physical examination, we performed a multivariate analysis to adjust for patient characteristics so we could determine whether the mode of detection was an independent predictor of treatment. As shown in Table 4, when the data are adjusted for patient age, menopausal status, and functional health status, the mode of detection still had a highly significant effect on the treatment received. After adjustment for patient covariates, women whose tumors were detected at physical examination were nearly three times as likely (odds ratio [OR], 2.9; 95% confidence interval [CI], 2.1–3.9) as women whose tumors were detected on screening mammography to be treated with chemotherapy and were 2.5 times as likely (OR, 2.5; 95% CI, 1.9–3.3) to be treated with mastectomy rather than breast conservation.
TABLE 4 Likelihooda of Mastectomy Versus Lumpectomy and Chemotherapy Versus No Chemotherapy According to Mode of Presentation: Physical Examination Versus Screening Mammography
Age Group (yr)Odds Ratio (CI)
Mastectomy vs LumpectomyChemotherapy vs No Chemotherapy
   40-491.4 (0.8-2.4)2.3 (1.3-4.0)
   50-692.5 (1.7-3.8)3.1 (2.1-4.7)
   ≥ 705.8 (3.2-10.5)4.6 (1.6-13)
All patients
2.5 (1.9-3.3)
2.9 (2.1-3.9)
Note.-CI = confidence interval.
a
Using multivariate analysis
Using this same multivariate analysis to adjust for patient characteristics, we found that women in the 40- to 49-year-old group whose cancer was detected at physical examination were more than twice as likely (OR, 2.3; 95% CI, 1.3–4.0) to be treated with chemotherapy than the group with tumors detected on screening mammography. In multivariate analysis, women in the 40- to 49-year-old age group whose cancer was detected at physical examination were not more likely to be treated with mastectomy (OR, 1.4; 95% CI, 0.8–2.4). In multivariate analysis, women in the 50- to 69-year-old age group whose tumors were detected at physical examination were three times more likely to be treated with chemotherapy (OR, 3.1; 95% CI, 2.1–4.7) and were 2.5 times as likely to undergo mastectomy (OR, 2.5; 95% CI, 1.7–3.8).
The greatest relative differences in treatment were seen in the oldest age group. In multivariate analysis, women in the 70-year-old or older age group whose tumors were detected at physical examination were over four times more likely to be treated with chemotherapy (OR, 4.6; 95% CI, 1.6–13) and more than five times as likely to be treated with mastectomy (OR, 5.8; 95% CI, 3.2–10.5) than women whose tumors were detected on screening mammography.

Discussion

Many factors need to be considered by women when making the decision about whether to undergo screening mammography and by providers when counseling women regarding this decision. Potential benefits include decreased mortality from breast cancer, a greater opportunity to undergo breast-conserving surgery, and a decreased likelihood to receive chemotherapy and its associated morbidity. Potential harms of screening include anxiety, the expense of mammography, and morbidity associated with diagnostic biopsies for false-positive mammograms. Our study is noteworthy because we found that women with breast cancer diagnosed on screening mammography were more likely to receive less-invasive and less-toxic therapy than women whose breast cancers were found at physical examination.
Our study found that 36% of women 40–49 years old, 56% of women 50–69 years old, and 49% of women 70 years old or older had their cancer detected on screening mammography. These percentages are higher than those reported in most other studies. Schleicher and Ammon [7] in a 1998 German study found that only 16% of breast cancers were detected on screening mammography. Our increased likelihood of detection using screening mammography may be secondary to the increased use of screening mammography in the general population in our area. In Germany at the time of that study, 30–40% of women underwent screening mammography [7], whereas in New Hampshire approximately 70% of women 50 years old and older have had at least one screening mammogram [18]. The percentage of cancers detected on screening mammography also has been reported to be a function of patient age. For example, in a study that evaluated three regions in the United States, Coates et al. [19] found that only 20% of breast cancers in women 20–44 years old were detected on screening mammography. In contrast, a study of patients 65 years old and older indicated that 76% (99/130) of elderly patients had their tumors detected on mammography [20]. Our study in general supports these findings: A higher proportion of older women had their cancers detected on screening mammography. Our assessment of how the study population relates to a population-based sample of New Hampshire women helps support the generalizability of our findings, because it indicates that no systematic bias based on patient characteristics appears to exist in the data analyzed.
Multiple studies have shown that breast cancers detected on screening mammography are smaller and are more likely to be node-negative than tumors detected at physical examination [712]. Our study also found that the mode of detection was associated with dramatic differences in the mean diameters of the tumors and the percentage of patients with positive nodes. Our study has contributed new information in that we found one third of patients with cancer detected on screening mammography had tumors that were smaller than 1 cm in diameter and were node-negative, thereby placing them in a group for whom consensus guidelines would not recommend adjuvant chemotherapy [13]. In contrast, only 7% of patients whose cancer was detected at physical examination fall into this group.
Other studies also have reported that patients whose breast cancer is detected on screening mammography are more likely to undergo breast conservation [79, 11, 21]. Rates of breast conservation surgery in the mammography-detected groups in these studies range from 64% to 68%, compared with 45–54% of patients whose tumors were detected at physical examination. Our study confirms this benefit of screening mammography because we found that 56% of patients with cancer detected on screening mammography were treated with breast conservation compared with only 32% in the group with cancer detected at physical examination. We extended these observations by performing a multivariate analysis that adjusted for patient characteristics such as age, menopausal status, and functional health (Karnofsky performance status) and have shown that the mode of detection is an independent predictor of the extent of surgery. After adjusting for patient characteristics that might influence treatment, we found that patients who presented with a palpable mass were still more than twice as likely to undergo mastectomy as patients whose cancer was detected on screening mammography.
To our knowledge, only two previous studies have examined the relationship between the mode of detection of breast cancer and the administration of chemotherapy. Olivotto et al. [9] compared outcomes of women who attended at least one session of the Screening Mammography Program of British Columbia with nonattenders diagnosed with breast cancer. This study did not compare patients whose cancer was detected on screening mammography directly with those whose cancers were detected at physical examination; in fact, only 74% (1,962/2,647) of the cancers in the patients in the screening mammography program were detected on screening mammography, and an unspecified number of patients who did not participate in the screening mammography program had their cancers detected on screening mammography. That study found a statistically significant, but small, difference in the percentage of patients who received chemotherapy: 23% of the screening mammography program participants versus 27% of the nonparticipants.
Haffty et al. [10] evaluated the effect of the method of detection on treatment of patients in the 1980s. The relative difference in chemotherapy rates in their study was similar to ours: Patients were approximately half as likely to receive chemotherapy if their cancer was detected on mammography as those with cancer detected at physical examination. During the time of their study, 11% of the patients with cancer detected on mammography versus 21% of those with cancer detected at physical examination were treated with chemotherapy. Our study confirms and extends these findings. In the time period of our study (1990–2001), adjuvant chemotherapy was being used more frequently: in 28% of the patients with cancer detected on mammography and 56% of those with cancer detected at physical examination. Although the relative difference is the same as that found by Haffty et al., the absolute difference (10% in the Haffty study vs 28% in our study) is much greater, emphasizing the importance of these observations in our current treatment environment. Furthermore, we have extended these observations by using multivariate analysis to show that the mode of detection is an independent predictor of treatment with chemotherapy even when other patient characteristics are taken into account.
Much of the debate concerning the benefits of screening mammography concerns its use in the 40- to 50-year-old age group. Little data are available about the relationship between the mode of detection and therapy for this subgroup of patients. Maibenco et al. [8] showed that, in a group of 40- to 49-year-old breast cancer patients with 119 cases detected at physical examination and 40 on mammography, the mammographically detected tumors were smaller and less commonly node-positive [8]. In their study, patients with cancer detected on screening mammography were more likely to undergo breast conservation (67% vs 50%). Our study, which included 258 patients in that age group, extends their findings. We found that the tumors in the mammographically detected group were significantly smaller and more likely to be node-negative (Table 3). One third of the patients had tumors that were node-negative and smaller than 1 cm in diameter and therefore were not likely to be recommended to undergo chemotherapy. As described by Maibenco et al., we found that patients with cancer detected on screening mammography were more likely to be treated with breast conservation (52%) than patients whose cancers were detected at physical examination (38%). However, this difference was not found to be statistically significant in multivariate analysis when other patient characteristics were taken into account. Nevertheless, our analysis has identified a significant benefit for screening mammography in this patient subset: Patients 40–49 years old whose cancers are detected on screening mammography are less likely to be treated with chemotherapy (57% vs 75%, p = 0.003). This relationship was confirmed by multivariate analysis, which found that patients aged 40–49 whose cancer was detected at physical examination were more than twice as likely to be treated with chemotherapy (OR, 2.3; 95% CI, 1.3–4.0). Our findings provide supportive evidence in favor of screening mammography for women who are 40–49 years old.
Recommendations regarding screening mammography for patients 70 years old and older suffer from a lack of data. Only one study examining the survival benefit of screening mammography, the Swedish Two-County Trial [6], included patients in this age group; women eligible for that study were between 40 and 74 years old. Little data regarding the relationship between the mode of detection and therapy for this subgroup of patients are available. Solin et al. [20] studied a group of breast cancer patients over 65 years old; those researchers found that cancers in 107 patients were detected on screening mammography and cancers in 23 patients were detected at physical examination. Seventy percent of the patients with cancer detected on screening mammography were treated with breast conservation compared with 27% of the patients with cancer detected at physical examination. Our study, which included substantially more patients (113 with tumors detected on mammography; 117, at physical examination), found a similar relationship: 66% of patients with cancer detected on screening mammography were treated with breast conservation compared with only 27% of the patients with cancer detected at physical examination. In multivariate analysis, the mode of detection had the most marked effect on the treatment for elderly patients. Patients 70 years old and older who presented with a palpable breast cancer were over five times more likely to undergo mastectomy and nearly five times more likely to be treated with chemotherapy than elderly patients whose cancer was detected on screening mammography. These findings make a compelling case for the use of screening mammography in elderly patients.
In summary, we have shown in a study of 992 patients that screening mammography for the detection of invasive breast cancer allows tumors to be diagnosed at an earlier stage, thereby allowing patients who have developed breast cancer to be treated adequately with less-toxic therapy. These benefits are particularly striking in the patients for whom the survival benefits of screening mammography are most controversial: the 40- to 49-year-old age group and elderly women (≥ 70 years old).

Footnotes

Supported by the National Cancer Institute (grants CA 23108 and U01 CA 86082-01).
Address correspondence to R. J. Barth, Jr.

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Information & Authors

Information

Published In

American Journal of Roentgenology
Pages: 324 - 329
PubMed: 15615996

History

Submitted: March 12, 2004
Accepted: June 14, 2004

Authors

Affiliations

Richard J. Barth, Jr.
Department of Surgery, Section of General Surgery, Dartmouth-Hitchcock Medical Center, Dartmouth Medical School and the Norris Cotton Cancer Center, Lebanon, NH 03756.
Glen R. Gibson
Department of Surgery, Section of General Surgery, Dartmouth-Hitchcock Medical Center, Dartmouth Medical School and the Norris Cotton Cancer Center, Lebanon, NH 03756.
Patricia A. Carney
Department of Community and Family Medicine, Dartmouth-Hitchcock Medical Center, Dartmouth Medical School and the Norris Cotton Cancer Center, Lebanon, NH.
Leila A. Mott
Department of Community and Family Medicine, Dartmouth-Hitchcock Medical Center, Dartmouth Medical School and the Norris Cotton Cancer Center, Lebanon, NH.
Robert D. Becher
Department of Surgery, Section of General Surgery, Dartmouth-Hitchcock Medical Center, Dartmouth Medical School and the Norris Cotton Cancer Center, Lebanon, NH 03756.
Steven P. Poplack
Department of Radiology, Dartmouth-Hitchcock Medical Center, Dartmouth Medical School and the Norris Cotton Cancer Center, Lebanon, NH 03756.

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