Insurance Claims May Model Anti-HER2 Chemo Demand

A study including 10 million patients covered by 11 health plans suggested that insurance claims could be used to estimate the number of early-stage breast cancer cases as well as the demand for anti-HER2 drugs.

Analyzing health insurance claims may be an effective way to measure cases of early-stage breast cancer and breast cancer surgery, as well as to predict future demand for anti—human epidermal growth factor receptor 2 (HER2) chemotherapy, according to a study presented on October 16, 2013, at the Academy of Managed Care Pharmacy Nexus 2013: Connecting Health Care and Innovation Conference in San Antonio.

The study estimated the number of patients likely to receive anti-HER2 chemotherapy using health claims data from a population of 10 million patients covered by 11 health plans. The researchers separately calculated the portion of early-stage breast cancer patients who received trastuzumab in addition to primary treatment with surgery, the rate of primary breast cancer surgery (to determine the incidence rate of early-stage breast cancer), and the number of patients newly beginning treatment with trastuzumab (to estimate the demand for anti-HER2 therapy).

To determine the portion of early-stage breast cancer patients treated with surgery who also received trastuzumab, researchers selected a sample of patients younger than 65 who had a claim for lumpectomy or mastectomy in 2010 or 2011. Patients with claims for doxorubicin, cyclophosphamide, docetaxel, paclitaxel, fluorouracil, epirubicin, methotrexate, or carboplatin were identified as having received cytotoxic chemotherapy and were further categorized based on whether they had received trastuzumab therapy. Patients insured in 2010, 2011, or 2012 who were diagnosed with breast cancer and treated with trastuzumab were determined to have early-stage breast cancer if they began trastuzumab therapy 261 days before or after undergoing a lumpectomy or mastectomy. Patients without a claim for primary breast cancer surgery 261 days before or after initiating trastuzumab therapy were determined to have metastatic or recurrent breast cancer. To estimate the number of new trastuzumab cases, researchers determined the number of days between the start of cytotoxic chemotherapy and breast cancer surgery.

Of 5050 early-stage breast cancer patients treated with surgery, 51.7% also received cytotoxic chemotherapy. Among cytotoxic chemotherapy patients, 24.8% were treated with trastuzumab. Nearly 80% of these patients began treatment with trastuzumab after surgery, while 21% started treatment before surgery. The results indicated that 9498 patients underwent a primary breast cancer surgery and 1462 started new trastuzumab therapy. Among patients newly initiating trastuzumab treatment, most had breast cancer (96.2%), with 76% categorized as early-stage and 15.9% as metastatic.

Based on the finding that most patients starting trastuzumab therapy were treated for early-stage breast cancer, the researchers conclude that the use of new anti-HER2 agents for early-stage breast cancer would have a greater impact on costs than would their use in treating metastatic cancer. The researchers note that the rate for early-stage breast cancer found in the study is close to national breast cancer incidence rates, suggesting that commercial insurance claims data can be used to identify early-stage breast cancer cases.

“These findings can support modeling of future demand for anti-HER2 chemotherapy in commercially insured populations,” they write.