Reduction of elective lymph node volume in radiotherapy of early anal squamous cell cancer: a comparative study between two Swedish university hospitals.

BACKGROUND: Anal squamous cell cancer (ASCC) in early stages (T1-2N0M0) is treated with chemoradiotherapy with a 3-year overall survival (OS) exceeding 90%. In Swedish guidelines, it has been optional to include the external iliac and presacral lymph node (LN) stations in radiotherapy (RT) treatment fields in early ASCC. Two Swedish hospitals treating ASCC (SU: Sahlgrenska University Hospital; UU: Uppsala University Hospital) have chosen different approaches since 2010. MATERIAL AND METHODS: This study included consecutive patients with early ASCC (T1-2N0M0) treated between 2010 and 2017 at both sites (SU n = 70; UU n = 46). Data were retrieved from medical records and RT charts. RESULTS: At SU, the external iliac and presacral LN stations were included in elective LN irradiation in 96.8% (n = 60) and 95.2% (n = 59) patients compared to 2.4% (n = 1) and 29.3% (n = 12) at UU. The mean elective LN volume was 2,313 cc (interquartile range [IQR] 1,951-2,627) in the SU cohort compared to 1,317 cc (IQR 1,192-1,528) in the UU cohort, p < 0.0001. No case of regional LN recurrence was seen in either cohort. Disease specific survival (DSS) at 5 years was 95.7% (confidence interval [CI] 90.1-100.0) in the SU cohort and 97.8% (CI 93.2-100.0) in the UU cohort (p 0.55). OS at 5 years was 84.5% (CI 76.1-93.0) in the SU cohort and 82.6% (CI 69.6-89.1) in the UU cohort (p 0.8). INTERPRETATION: We found no differences in regional recurrence, DSS or OS between the cohorts treated with different elective LN volumes. In this population-based study, reduction of RT volume in early ASCC did not lead to inferior outcome.

Development of a consensus-based delineation guideline for locally recurrent rectal cancer.

BACKGROUND AND PURPOSE: Neoadjuvant chemoradiotherapy (nCRT) is used in locally recurrent rectal cancer (LRRC) to increase chances of a radical surgical resection. Delineation in LRRC is hampered by complex disease presentation and limited clinical exposure. Within the PelvEx II trial, evaluating the benefit of chemotherapy preceding nCRT for LRRC, a delineation guideline was developed by an expert LRRC team. MATERIALS AND METHODS: Eight radiation oncologists, from Dutch and Swedish expert centres, participated in two meetings, delineating GTV and CTV in six cases. Regions at-risk for re-recurrence or irradical resection were identified by eleven expert surgeons and one expert radiologist. Target volumes were evaluated multidisciplinary. Inter-observer variation was analysed. RESULTS: Inter-observer variation in delineation of LRRC appeared large. Multidisciplinary evaluation per case is beneficial in determining target volumes. The following consensus regarding target volumes was reached. GTV should encompass all tumour, including extension into OAR if applicable. If the tumour is in fibrosis, GTV should encompass the entire fibrotic area. Only if tumour can clearly be distinguished from fibrosis, GTV may be reduced, as long as the entire fibrotic area is covered by the CTV. CTV is GTV with a 1 cm margin and should encompass all at-risk regions for irradical resection or re-recurrence. CTV should not be adjusted towards other organs. Multifocal recurrences should be encompassed in one CTV. Elective nodal delineation is only advised in radiotherapy-naïve patients. CONCLUSION: This study provides a first consensus-based delineation guideline for LRRC. Analyses of re-recurrences is needed to understand disease behaviour and to optimize delineation guidelines accordingly.