Abstract
BackgroundAnal cancer is a rare disease, which might be the reason for the “one size fits all” approach still used for radiotherapy target contouring. To refine and individualize future guidelines, detailed and contemporary pattern of recurrence studies are needed.MethodsConsecutive anal cancer patients, all treated with curative intent intensity-modulated radiotherapy (IMRT), were retrospectively studied (n = 170). Data was extracted from medical records and radiological images. Radiotherapy planning CT’s and treatment plans were reviewed, and recurrences were mapped and categorized according to radiation dose.ResultsThe mean dose to the primary tumor was 59.0 Gy. With a median follow-up of 50 months (range 14–117 months), 5-year anal cancer specific survival was 86.1%. Only 1 of 20 local recurrences was located outside the high dose (CTVT) volume. More patients experienced a distant recurrence (n = 34; 20.0%) than a locoregional recurrence (n = 24; 14.1%). Seven patients (4.2%) had a common iliac and/or para-aortic (CI/PA) recurrence. External iliac lymph node involvement (P = 0.04), and metastases in ≥3 inguinal or pelvic lymph node regions (P = 0.02) were associated with a 15–18% risk of CI/PA recurrence. Following chemoradiotherapy, 6 patients with recurrent or primary metastatic CI/PA lymph nodes were free of recurrence at last follow-up. The overall rate of ano-inguinal lymphatic drainage (AILD) recurrence was 2 of 170 (1.2%), and among patients with inguinal metastases at initial diagnosis it was 2 of 65 (3.1%).ConclusionsWe conclude that other measures than increased margins around the primary tumor are needed to improve local control. Furthermore, metastatic CI/PA lymph nodes, either at initial diagnosis or in the recurrent setting, should be considered potentially curable. Patients with certain patterns of metastatic pelvic lymph nodes might be at an increased risk of harboring tumor cells also in the CI/PA lymph nodes.
Highlights
Anal cancer is a rare disease, which might be the reason for the “one size fits all” approach still used for radiotherapy target contouring
The extent of the elective clinical target volume (CTV) varies with TNM stage and primary tumor location [10], and in cervical carcinoma, the cranial border varies with the risk of para-aortic recurrence [11]
This study investigated patterns of recurrence in a relatively large cohort of anal cancer patients treated with modern radiotherapy techniques
Summary
Anal cancer is a rare disease, which might be the reason for the “one size fits all” approach still used for radiotherapy target contouring. Squamous cell carcinoma of the anal region (anal cancer) is a rare malignancy that is usually treated with chemoradiotherapy (CRT). Current international guidelines do not recommend different cranial borders of the elective clinical target volume (CTV) based on the risk of recurrence [7,8,9]. Nilsson et al Radiation Oncology (2020) 15:125 This is in contrast to guidelines for squamous cell carcinomas of other primary locations. The extent of the elective CTV varies with TNM stage and primary tumor location [10], and in cervical carcinoma, the cranial border varies with the risk of para-aortic recurrence [11]. The cranial border according to UK guidelines is 20 mm above the inferior aspect of the sacroiliac joint or 15 mm above the most superior aspect of the gross tumor, whichever is most superior
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