Re-referral for post-op radiation in elderly breast cancer patients who initially omit RT but are unable to tolerate endocrine therapy.

Abstract

e12507 Background: Omission of Radiation in the setting of Elderly patients 70 yo and above with ER+, cN0, pT1 tumors who receive adjuvant endocrine therapy (HT) is standard of care per NCCN. However, the average adherence rate of HT ranges from 41% to 72%, which is not optimal for patient outcomes. In our institution, we evaluated the treatments of all patients who qualified for omission of radiation upfront and the number of re-referrals for adjuvant radiation in Elderly Breast cancer patients who were unable to tolerate HT past 6 months. Methods: Data was obtained through the National Cancer Registry at our institution for 2021 and reviewed mid 2022. Inclusion criteria included patients diagnosed with Pathologically Invasive Breast Cancer AJCC Stage I-IIB age 70 and above. A total of 176 patients were eligible for review. 86 patients did not qualify for inclusion into study due to 7 receiving surgical treatment outside our system. Furthermore, 81 patients did not qualify due to the following reasons or combination: Mastectomy (19), Triple Negative, Greater than 2 cm, N+, AI only. A total of 90 patients qualified for omission and review. Six month HT therapy cut off was extrapolated by Barbieri et al who determined a 6 month delay of RT after surgery was not associated with an increased risk of relapse. Results: From the 90 patients who qualified for omission of radiation, 67 % (n = 60) of patients chose radiation omission, 30% (n = 27) of patients chose upfront radiation, and 3% (n = 3) of patients declined all therapy. Of the 60 patients who chose omission, 87% of patients had continued HT, however 2 patients passed away within 1 year of surgery. A total of 13% of patients (n = 8) who omitted radiation did not go past 6 months of HT, and only 2 out of 8 patients (25%) were referred back to radiation oncology and moved forward with treatment. For the 27 patients who chose radiation upfront even though they qualified for omission, the most common reason per records was the patient was unsure after initial multidisciplinary clinic that they would be able to tolerate HT. Interestingly, 27% of these patients ended up stopping HT within 9 months due to side effects. Conclusions: Omission of radiation is an option for Elderly Early stage breast cancer patients in the setting of HT. However, HT compliance is variable due to side effects. In our one year single institution study, only 25% of patients who omitted RT and did not get past 6 months of HT were sent back for radiation. We encourage an increased awareness and communication between Radiation Oncology and Medical Oncology regarding the option of radiation for patients who do not pass 6 months of HT. Our institution has implemented an Epic message system and Breast Navigation to aid in re-referral. It is also imperative at the time of Radiation Oncology consultation to discuss the possibility of intolerance to HT in the setting of omission may indicate radiation therapy at a later date.