ESTRO 2022

Session Item

Sunday

May 08

10:30 - 11:30

Poster Station 2

12: GI

Chair: , Italy

Session Type: Poster Discussion

Track: Clinical

Journey:

Patterns of failure in anal cancer after IMRT and chemotherapy: Impact of 1 vs 2 doses of Mitomycin.

Zainab Al Habsi, Canada

Presentation Number: PD-0501

Abstract

Abstract Title:

Patterns of failure in anal cancer after IMRT and chemotherapy: Impact of 1 vs 2 doses of Mitomycin.

Authors:

Zainab Al Habsi¹, Kurian Joseph², Aswin Abraham³, Mustafa Al Balushi³, Gabriella Tankel⁴, Karen Mulder⁵, Heather Warkentin⁶, Dan Schiller⁷, Keith Tankel⁸, Nawaid Usmani⁸, Diane Severin³, Kim Paulson³, Hatim Karachiwala⁹, Clarence Wong¹⁰, Tirath Nijjar³, Corinne Doll¹¹

¹Cross Cancer Institute , Radiation Oncology, Edmonton, Canada; ²Cross Cancer Institute, Radiation Oncology, Edmonton , Canada; ³Cross Cancer Institute, Radiation Oncology, Edmonton, Canada; ⁴University of Alberta, Research, Edmonton, Canada; ⁵Cross Cancer Institute, Medical Oncology, Edmonton, Canada; ⁶Cross Cancer Institute, Medical Physics, Edmonton, Canada; ⁷Royal Alexandra Hospital, General Surgery, Edmonton, Canada; ⁸Cross Cancer Institute, Radiation Oncology , Edmonton, Canada; ⁹Cross Cancer Institute, Medical Oncology , Edmonton, Canada; ¹⁰Royal Alexandra Hospital, Gastroenterology, Edmonton, Canada; ¹¹TOM BAKER CANCER CENTRE, Radiation Oncology, Calgary, Canada

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Purpose or Objective

Concurrent chemoradiation (CRT) with 2 doses of 5-fluorouracil (5-FU) and mitomycin C (MMC) is the standard of care for anal canal cancer (ACC) in North America, while 1 dose of MMC has been standard in Europe. Given the lack of randomized data of 1 vs. 2 doses of MMC on disease outcomes, we have conducted a population-based study to elucidate the impact of 1 vs. 2 doses of MMC on patterns of treatment failure (POF) and outcomes in ACC treatment.

Material and Methods

Data was collected from the provincial cancer registry of patients with stage I-III ACC who were treated with concurrent CRT from 2000 to 2018. Primary outcome measures were patterns of failure, recurrence free survival (RFS) and overall survival (OS).

Results

428 patients with a median age of 58 years (29-88 years) were included in this analysis. 234 (54.7%) patients received 1 dose of MMC and 194 (45.3%) received 2 doses of MMC. At a median follow-up of 78.5 months (5-252 months), 89 (20.8%) patients developed disease recurrence: 44 (10.3%) loco-regionally, 39 (9.1%) distally and 6 (1.4%) had both local and distant recurrences. Cox regression analysis showed that the dosage of MMC did not have an impact on overall recurrence (HR=0.883, p=0.561), with the exception of patients with stage III disease who had a significantly higher risk of recurrence (HR=5.238, p=0.021). Subgroup analysis showed an association between stage IIIB and IIIC with recurrence (HR=13.33, p=0.008 and HR=6.933, p=0.011 respectively), but was not impacted by the use of 1 vs. 2 doses of MMC. The dosage of MMC was not associated with incidence of local recurrence (HR=1.136, p=0.655) or distant recurrence (HR=0.743, p=0.267). However, in Stage IIIC patients, 2 doses of MMC showed a trend towards improved distant RFS (HR=0.626, p=0.084). The median RFS and OS were not reached for either groups. The mean RFS was 192.2 and 200.6 months for 2 MMC and 1 MMC respectively (p=0.864). The mean OS was 171.8 and 182.4 months for 2 MMC and 1 MMC respectively (p=0.758).

Conclusion

Our analysis showed that the patterns of failure and the risk of loco-regional and distant failures were similar between ACC patients who received 1 vs. 2 doses of MMC for stage groups I to IIIC disease. These finding support routine use of single dose of MMC with 5FU and radiotherapy for definitive CRT. However, a trend towards better RFS was demonstrated with a second dose of MMC in patients with stage IIIC disease.