Background: Specialty referral rates have been steadily increasing, as much as 94% within a 10-year period (1). Previous studies have shown the benefits of specialty referral in oncology management in specific populations such as lung cancer patients (2). However, there have yet to be larger-scale studies on general trends in specialty referral in oncology. In particular, patients on immune checkpoint inhibitors frequently develop immune-related adverse events (irAEs) affecting a variety of organ systems and may benefit from specialty care (3).

Objectives: To evaluate the patterns of specialty referral in patients treated with immune checkpoint inhibitors and identify referral patterns that affect patient outcomes.

Methods: This was a retrospective study of all specialty referral for patients on an immunotherapy regimen from 6/1/2022-6/1/2023 at a single-institution cancer center. The specialties consulted included cardiology, dermatology, endocrinology, gastroenterology, infectious disease, neurology, pulmonology, and nephrology.

Results: In total, there were 5,602 patients on an immunotherapy regimen, of whom 3,519 patients (62.8%) were referred to a specialist. Of these patients, 2,017 (57.3%) attended a specialist appointment. A majority of the patients were male (n=1038, 51.5%), had a mean age of 64.1 years (SD=13.8) at initial consult, and were White/non-Hispanic (n=1414, 70.1%). The mean and median number of consults per patient were 1.7 (SD=1.3) and 1 (IQR=1), respectively. The maximum number of consultations for a patient was 17. Dermatology was the most commonly consulted service (n=841, 25.9%), followed by neurology (n=781, 24.0%), and endocrinology (n=446, 13.7%). For dermatology, the most common reason for consultation was evaluation of a rash (n=500, 59.5%). Dermatology also had the highest ratio of outpatient to inpatient consultations at 10.4 to 1. The next closest service was endocrinology at 3.0 to 1. The pulmonary service had the shortest time between consult request and patient visit (10 days), followed by dermatology (13 days), and gastroenterology (15 days). Prior to their initial consultation, the vast majority of patients (82.6%) were on a single therapy, and the most common single therapy was pembrolizumab (n=1589, 59.2%). The most common combination therapy was ipilimumab plus nivolumab, accounting for 59.3% of combinations. Fifty percent of patients (n=1008) who saw a specialist were able to continue their immunotherapy regimen.

Conclusions: There is a range of specialty and multidisciplinary care that is necessary for the management of patients on immunotherapy regimens.

Citation Format: Anna Chen, Stephen Dusza, David Faleck, Neil Shah, Mario E. Lacouture. Patterns of specialty referral in cancer patients treated with immunotherapy regimens [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 924.