Adjuvant Treatment Decisions among Adults Aged 65 Years and Older with Early-Stage Hormone Receptor Positive Breast Cancer Seen in a Simple Multidisciplinary Clinic Versus Standard Consultation.

Introduction: Randomized studies support de-escalation of adjuvant therapy for a target population of older adults >= 65 years with stage I, estrogen-receptor (ER) positive breast cancer after breast conserving surgery. We sought to evaluate the impact of a simplified multidisciplinary clinic (s-MDC) in this population by comparing treatment patterns and patient perceptions of adjuvant radiation therapy (RT) and hormone therapy (HT) between patients seen in s-MDC vs. standard consultations.Materials and Methods: Medical records were retrospectively reviewed for patients in the above target population who underwent surgery between August 2020 and May 2022 at our institution. Two cohorts were included: (1) patients seen in s-MDC, and (2) patients seen in standard clinic separately by medical and radiation oncology (non-s-MDC cohort). The non-s-MDC patients declined, could not attend, and/or were not referred to the s-MDC. Patients in the s-MDC cohort were prospectively administered validated questionnaires to evaluate patient re-ported data including the Decision Autonomy Preference Scale (DAPS), e-Prognosis, and Medical Maximizing -Minimizing Scale (MMS). Chi square, t-tests, and non-parametric equivalents compared demographics, and lo-gistic regression evaluated RT and HT use and survey score outcomes between cohorts.Results: A total of 127 patients met inclusion criteria, with 33 s-MDC and 94 non-s-MDC patients. There was no difference between the cohorts in age, margin status, histology, grade, or focality. In the s-MDC cohort there were significantly more patients without sentinel lymph node biopsy (71.3% vs 42.4%, p = 0.003) and mean tumor size was smaller (0.69 vs. 0.96 cm, p < 0.003), and Charlson comborbidity index (CCI) was higher (5.21 vs 4.96, p = 0.038). There was no significant difference in receipt of RT (65% s-MDC vs 77% standard; odds ratio [OR] = 0.55, p = 0.189), HT (78% ss-MDC vs 72% standard; OR = 1.36, p = 0.513), or both (50% s-MDC vs 59% standard; OR = 0.7, p = 0.429). The s-MDC cohort was significantly more likely to undergo accelerated (vs. standard hypofractionated) RT (70% vs 39%; OR = 3.59, p = 0.020). In s-MDC patients with completed ques-tionnaires (n = 33), all whose selected "mostly patient (n=6)" based decision making by DAPS chose RT while all "mostly doctor (n=1)" chose no RT. Based on e-Prognosis, there were lower odds of RT for increasing Schonberg score/ higher 10 yr mortality risk (OR 0.600, p = 0.048). MMS score >= 40 ("maximizer") was strongly linked with the use of RT (OR 18.57, p = 0.011).Discussion: For adults >= 65 years with early stage, ER positive breast cancer, s-MDC participation was not significantly associated with lower use of adjuvant RT or HT versus standard consultation but was significantly associated with shorter RT courses. DAPS and MMS results indicate that patient treatment preference may be predictable, highlighting an opportunity to tailor consultation discussions and recommendations based on intrinsic patient preferences and individual goals.