DOI:10.2214/AJR.06.5076.1
AJR 2006; 187:W553
© American Roentgen Ray Society
Reply
T. Thomas Zacharia and
Sanjay Saini
Massachusetts General Hospital Present address: Elmhurst, NY
11373
Massachusetts General Hospital Boston, MA 02114
WEB—This is a Web exclusive article.
We thank Dr. Schwartz and colleagues for their interest in our article on
the minimum number of hepatic metastatic lesions that must be measured to
assess patient response to therapy
[1]. We would like to address
their concerns regarding the methodology used and conclusions derived.
Our patient population was highly selective because the objective of our
study was to redefine the minimum number of target lesions to be measured per
organ. Other sites of metastases such as lungs and lymph nodes should be
evaluated to determine patient response. The RE-CIST group (Response
Evaluation Criteria in Solid Tumors Group)
[2] states that all measurable
lesions up to a maximum of five lesions per organ and 10 lesions in total,
representative of all involved organs, should be identified as target lesions
and recorded and measured at baseline. We emphasized the fact that assessing
therapeutic response on the basis of hepatic metastases alone would not be
accurate in several patients with metastatic colon cancer.
Colon cancer metastases to the liver can be either well defined and
homogeneous or ill defined and heterogeneous, or a combination of both
patterns of lesions. By measuring the well-defined homogeneous lesions, we can
reduce the variability in measurements and give a more accurate assessment of
treatment response. We concluded that response evaluation with two large,
well-defined lesion measurements gave 100% concordant results to response with
five target-lesion measurements and that single-lesion measurements gave
concordant disease response when compared with multiple-lesion measurements in
93.33% of evaluations [1].
Our study was designed based on the new guidelines validated by the RECIST
Group [2]. In the current
guidelines, the section on response criteria (3.2. Response Criteria,
3.2.1. Evaluation of target lesions) provides the definitions of the criteria
used to determine objective tumor response for target lesions. The criteria
have been adapted from the original WHO Handbook
[3], taking into account the
measurement of the longest diameter only for all target lesions. The formula
provided by Schwartz and colleagues could be useful for calculating the
increase in variability that results when a selective group of tumors, rather
than all available tumors, is selected for measurement
[4].
A recent investigation by Therasse et al.
[5] reviews the literature (a
total of 60 articles) that has been published on RECIST from 2000 up to
November 2005. They conclude that there is no universal method available as of
now for tumor measurement. The findings of their review, together with the
results of ongoing studies, will probably result in the presentation of an
updated version of RECIST later this year
[5].
References
- Zacharia TT, Saini S, Halpern EF, Sumner JE. CT of colon cancer
metastases to the liver using modified RECIST criteria: determining the ideal
number of target lesions to measure. AJR2006; 186:1067
-1070[Abstract/Free Full Text]
- Therasse P, Arbuck SG, Eisenhauer EA, et al. New guidelines to
evaluate the response to treatment in solid tumors: European Organization for
Research and Treatment of Cancer, National Cancer Institute of the United
States, National Cancer Institute of Canada. J Natl Cancer
Inst 2000; 92:205
-216[Abstract/Free Full Text]
- WHO handbook for reporting results of cancer
treatment. Geneva, Switzerland: World Health Organization Offset
Publication No. 48; 1979
- Mazumdar M, Smith A, Debroy PP, Schwartz LH. A theoretical approach
to choosing the minimum number of multiple tumors required for assessing
treatment response. J Clin Epidemiol2005; 58:150
-153[CrossRef][Medline]
- Therasse P, Eisenhauer EA, Verweij J. RECIST revisited: a review of
validation studies on tumour assessment. Eur J Cancer2006; 42:1031
-1039[CrossRef][Medline]
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