Systemic treatment patterns in small bowel and appendiceal adenocarcinomas (SBA and AA): A population-based study.
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242 Background: There is uncertainty regarding the optimal systemic treatment for patients with SBA and AA due to the limited available evidence for these uncommon malignancies and conflicting recommendations in existing guidelines. However, on the basis of biologic similarities between SBA, AA and colorectal cancer (CRC), common practice is to use the same systemic therapies as for CRC. We compared the utilization of chemotherapeutic agents for SBA and AA to that of CRC patients in Ontario, Canada. Methods: The provincial tumour registry in Ontario, Canada was used to identify patients diagnosed with SBA, AA or CRC from 2010-2014. Subsequent chemotherapy utilization and costs were captured from single-payer government administrative databases. We studied the use of oxaliplatin, irinotecan, capecitabine, bevacizumab, cetuximab, panitumumab, and raltitrexed, which are funded for CRC treatment. Patients were excluded if they had multiple primary cancer sites, morphology codes inconsistent with adenocarcinomas, or missing identification data. Statistical analyses were used to report and test patterns of utilization and average costs per patient. Results: Our cohort consisted of 30,946 patients over a 5-year period. On average, 160 and 80 patients were diagnosed annually in Ontario with SBA and AA, respectively, together representing less than 4% of the total diagnoses each year. Among SBA and AA patients, 30-40% initiated therapy with the selected systemic therapies, similar to the proportion in CRC. SBA and AA patients were less likely to receive adjuvant oxaliplatin (SBA 9%, AA 13%) compared to CRC (18%) patients, but more likely to use first and second-line oxaliplatin or irinotecan for metastatic disease. Bevacizumab was added to first-line therapy for SBA and AA patients in fewer cases than CRC (SBA 29%, 45% AA, 72% CRC). Third-line EGFR inhibitors panitumumab and cetuximab were used infrequently in all groups ( < 2% of those diagnosed). Average per patient costs were similar across disease sites (p > 0.05). Conclusions: On a population level, SBA and AA patients appear to be managed similarly to CRC patients and at similar cost. Future research will evaluate survival outcomes.
