Background: The proliferation of novel treatment options has placed an increased emphasis on our need to better understand the variability in treatment choice and treatment patterns in oncology. The objective of this study was to characterize the variability in cancer treatment patterns for breast, colorectal and lung cancer. Methods: Pre-authorization requests for chemotherapy and/or targeted cancer treatments were utilized to identify breast, colorectal and lung cancer patients between 6/1/2014 and 4/30/2015 within the integrated clinical oncology and administrative claims data of the HealthCore Integrated Research Environment (HIRE) - Oncology. The earliest pre-authorization date was assigned as the index date. Demographics were evaluated by cancer type. Clinical characteristics and treatment patterns were assessed by cancer type and line of treatment. Results: 3,116 breast, 1,241 colorectal and 1,200 lung cancer patients were identified with mean ages of 52.6± 9.9, 55.5±9.3 and 60.3±8.1 years, respectively. Stage IV was most prevalent among colorectal (67%) and lung (74%) cancer patients and stage II among breast cancer patients (36%). Across breast (82%), colorectal (72%) and lung (74%) cancers, 1^st line therapy represented the majority of pre-authorization requests. Among breast cancer patients, the most common 1^st, 2^nd and +3^rd line therapies were docetaxel/cyclophosphamide (17%), fulvestrant (20%) and eribulin (18%), respectively. Among colorectal cancer patients, the most prevalent 1^st, 2^nd, and +3^rd line therapies were fluorouracil/leucovorin/oxaliplatin (35%), fluorouracil/leucovorin/irinotecan/bevacizumab (29%), and irinotecan/cetuximab (20%), respectively. In lung cancer, the most common 1^st, 2^nd and +3^rdline therapies were pemetrexed/carboplatin (19%), docetaxel (20%) and gemcitabine (20%). Conclusions: There was extensive variation in treatment patterns among breast, colorectal and lung cancer patients, particularly within 1^st line therapy which represented the majority within each cancer type. This study provides initial insight on the relative generalizability of treatments requested by physicians participating within Anthem’s CCQP.