e-Poster Presentation Clinical Oncology Society of Australia Annual Scientific Meeting 2020

Is adjuvant pelvic radiation therapy after local excision or polypectomy for T1 and T2 rectal cancer an appropriate treatment approach? (#245)

Carmen Swanton 1 , Sapna Marcus 1 , Jayasingham Jayamohan 1 2 , Nimalan Pathma-Nathan 3 , Toufic El-Khoury 2 3 4 , Mark Wong 2 5 , Adnan Nagrial 2 5 , Drew Latty 1 , Puma Sundaresan 1 2
  1. Radiation Oncology Network, Westmead Hospital, Sydney, NSW
  2. Sydney Medical School University of Sydney. The University of Sydney , Sydney, NSW
  3. Department of Colorectal Surgery. Westmead Hospital , Sydney, NSW
  4. School of Medicine. University of Notre Dame, Sydney, NSW
  5. Department of Medical Oncology. Westmead Hospital, Sydney, NSW

Is adjuvant pelvic radiation therapy after local excision or polypectomy for T1 and T2 rectal cancer an appropriate treatment approach?

To determine outcomes after adjuvant pelvic local radiation therapy (RT) for T1 and T2 rectal carcinomas that were incidentally detected at time of local excision or polypectomy.

We retrospectively identified adult patients with histologically-proven T1 and T2 rectal adenocarcinoma, diagnosed incidentally at time of local excision or polypectomy between 01 January 2007 and 31 December 2019, and appropriately staged to confirm N0 M0 status. Patients were excluded if they had recurrent cancer or received definitive oncological surgical interventions – anterior resection (AR) or abdominoperineal resection (APR). Patient, tumour and treatment factors, together with disease and toxicity outcomes were collected from institutional medical records, correspondence and investigation reports. Descriptive statistical analyses were employed. The primary endpoint was loco-regional control and secondary endpoints were treatment-related toxicity, disease free survival, overall survival and rate of surgical salvage for pelvic recurrence.

The median age of the 15 eligible patients was 73 (range 49-82 years). There were 9 men (60%) and 6 women (40%). Most (80%) had T1 disease and 80% had received endomucosal resection. All patients received 43-52Gy (EQD2) to the primary and 43-48Gy (EQD2) to the pelvis  with 46.6% receiving concurrent chemotherapy (infusional 5-FU or oral capecitabine).  At median follow up of 50.5 months, there were no local or regional recurrences but 1 distant relapse at 48 months.  

Our findings demonstrate good locoregional disease control with the use of adjuvant pelvic RT for T1 and T2 rectal adenocarcinoma detected incidentally at time of polypectomy or local (non-oncological) excision. These findings indicate that pelvic RT may provide an alternative to further definitive surgery such as AR or APR in these incidentally detected early rectal cancers.