ASSOCIATION BETWEEN THE AVAILABILITY OF MEDICAL ONCOLOGISTS AND RECEIPT OF CHEMOTHERAPY

Purpose: To determine the association between the availability of medical oncologists within the health service area (HSA) in which the patient resides and receipt of chemotherapy treatment.

Methods: Using data from the linked Surveillance, Epidemiology, and End results (SEER) – Medicare database, we identified patients diagnosed with TNM stage III or IV colon cancer during 2000 to 2005 who survived six months or more and underwent cancer-directed surgery within three months of diagnosis and initiated chemotherapy within three months after surgery.  Medical oncologists were identified by physician specialty code.  HSAs were geographic areas where medical resources were distributed and used based on the analysis of travel patterns between counties for routine hospital care.  Multivariate logistic regression was used to investigate the association between the availability of medical oncologists and receipt of chemotherapy after adjusting for clinical and patient characteristics. 

Results: Among 11,808 patients, 7.57% of them resided in a HSA with no medical oncologists; 14.22% with one to three oncologists; 18.67% with four to eight oncologists; 59.54% with nine or more oncologists.  7,274(61.6%) received chemotherapy after cancer-directed surgery.  Residing in a HSA with four or more medical oncologists was associated with an increased likelihood of receiving chemotherapy after surgery compared to areas with no medical oncologists (4-8 oncologists: OR=1.291, p<.01; 9+ oncologists: OR=1.283, p<.01).  Patients who were older than 70 years (p<.0001), African American (p<.001), currently not married (p<.0001), dually eligible for Medicare and Medicaid (p<.0001), with more comorbid conditions (p<.0001), and diagnosed in year 2005 (p<.01) had a decreased likelihood of receiving chemotherapy after surgery. Residing in the Northeast or South was associated with an increased likelihood of receiving chemotherapy versus residing in the West (p=.01 and p=.03, respectively). 

Conclusions: The availability of four or more medical oncologists within the HSA in which the patient resides was associated with greater access to chemotherapy after surgery.  Appropriate interventions to increase accessibility to chemotherapy include educational outreach efforts to primary care physicians in HSAs with three or less medical oncologists to strengthen referral networks or transportation assistance for patients.