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Journal of Clinical Oncology, Vol 26, No 4 (February 1), 2008: pp. 688-689 © 2008 American Society of Clinical Oncology. DOI: 10.1200/JCO.2007.15.0714
In ReplyDepartment of Radiation and Cellular Oncology and The Cancer Research Center, University of Chicago, Chicago, IL We thank Dirk Vordermark, MD, for the interest that he has shown in our recent publication, "Concurrent Chemotherapy and Intensity-Modulated Radiation Therapy for Anal Canal Cancer Patients: A Multicenter Experience," previously published in this journal.1 Intensity-modulated radiation therapy (IMRT) is a radiotherapy planning and delivery tool that aims to improve the radiation delivered to oncology patients.2 While a broad literature exists on the benefits of this technology to patients with prostate cancer3 and head and neck cancer,4 less attention has been directed to applying this technology to patients with pelvic malignancies, for whom it may be beneficial in reducing gastrointestinal and genitourinary toxicity.5,6
In our article, we tested the hypothesis that treatment-limiting acute gastrointestinal and dermatologic toxicity could be reduced by purposefully reducing radiation dose to the small bowel, bladder, and genitalia using IMRT for patients with anal canal cancer receiving concurrent chemotherapy and radiotherapy. The hypothesis was supported with a reduction in acute grade We agree with Dr Vordermark that the manuscript is confusing, stating that the skin was used as a sparing structure and subsequently stating, "1-cm bolus was used over the inguinal areas for elective treatment in all cases." This was an error in the manuscript and has been corrected with an erratum. When needed, customized tissue equivalent material was used to ensure adequate dosing to nodal structures, and not routinely or electively used. In his letter, Dr Vordermark raises a number of apprehensions regarding the utility of concurrent chemotherapy and IMRT for treatment of patients with anal canal cancer. One possible concern is that that the area of gross tumor (being the anus and perianal skin) will be under-dosed in an attempt to decrease dermatologic toxicity. However, as described in the methods of our study, coverage of the perianal region and nodal targets were considered to be the highest planning priorities, before sparing of any nearby organs such as the small intestine, bladder, genitalia, and skin. When we initiated treatments with IMRT for anal canal cancer patients, we too were concerned that the radiation doses could be delivered accurately and reliably to the perianal region. Our data with our first three patients with body-mass indexes ranging from 20 to 35 demonstrate a measured delivered dose over three consecutive treatments to within 5% of the predicted dose. These data demonstrate that the dose planned to be delivered and immobilization techniques employed correctly delivered the dose to within the error range of the thermoluminescent dosimetry devices (unpublished data, Julius Turian, December 2000). It seems that the natural anatomic shape and location of the anus within the gluteal folds ensures adequate dose delivery.
While 42% of patients required a treatment break, few required longer than 3 days, and the median time to completion of treatment was 6 weeks. Therefore, treatments were delivered in a timely fashion, and treatment interruptions were limited in duration. Furthermore, the majority of treatment interruptions were for hematologic toxicity, per the standards of large cooperative groups. While Dr Vordermark points to a study with extremely low rates of acute grade We agree that complex 3D conformal radiotherapy techniques can deliver similar radiation dose patterns. However, one added advantage of IMRT is simplicity of radiation delivery. Furthermore, not all patients with anal cancer are candidates for IMRT concurrently with chemotherapy. In obese patients with nonreproduceable external skin contours, IMRT would not be recommended. The optimization of IMRT needs to continue integrating bone marrow sparing to reduce hematologic toxicity events decreasing treatment interruptions due to neutropenia. However, in its current form, IMRT can be delivered safely and effectively with high rates of control and data demonstrating proper dosing to the primary tumor and perianal skin. Editor's Note An erratum has been published in this issue to correct the error in the Patients and Methods section of the article (J Clin Oncol 25:4581-4586, 2007). AUTHORS' DISCLOSURES OF POTENTIAL CONFLICTS OF INTEREST The author(s) indicated no potential conflicts of interest. REFERENCES
1. Salama JK, Mell LK, Schomas DA, et al: Concurrent chemotherapy and intensity-modulated radiation therapy for anal canal cancer patients: A multicenter experience. J Clin Oncol 25:4581-4586, 2007 2. Teh BS, Woo SY, Butler EB: Intensity modulated radiation therapy (IMRT): a new promising technology in radiation oncology. Oncologist 4:433-442, 1999 3. Zelefsky MJ, Fuks Z, Leibel SA: Intensity-modulated radiation therapy for prostate cancer. Semin Radiat Oncol 12:229-237, 2002[CrossRef][Medline] 4. Eisbruch A, Ship JA, Dawson LA, et al: Salivary gland sparing and improved target irradiation by conformal and intensity modulated irradiation of head and neck cancer. World J Surg 27:832-837, 2003[CrossRef][Medline] 5. Salama JK, Roeske JC, Mehta N, et al: Intensity-modulated radiation therapy in gynecologic malignancies. Curr Treat Options Oncol 5:97-108, 2004[CrossRef][Medline] 6. Mundt AJ, Lujan AE, Rotmensch J, et al: Intensity-modulated whole pelvic radiotherapy in women with gynecologic malignancies. Int J Radiat Oncol Biol Phys 52:1330-1337, 2002[CrossRef][Medline] 7. Vuong T, Kopek N, Ducruet T, et al: Conformal therapy improves the therapeutic index of patients with anal canal cancer treated with combined chemotherapy and external beam radiotherapy. Int J Radiat Oncol Biol Phys 67:1394-1400, 2007[Medline]
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Copyright © 2008 by the American Society of Clinical Oncology, Online ISSN: 1527-7755. Print ISSN: 0732-183X
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3 dermatologic and gastrointestinal toxicity compared with large cooperative group studies. This same hypothesis is currently being tested in the Radiation Therapy Oncology Group cooperative group setting. 
