Women insured by Medicaid were more likely to undergo mastectomy for early-stage breast cancer than those who were privately insured in a single integrated healthcare system, researchers found.

The mastectomy rate was lower among women with Medicaid for tumors smaller than 2 cm but higher in that group for larger tumors, resulting in a significantly higher mastectomy rate overall compared with their counterparts with private insurance (60% versus 39%, P<0.05), according to Joseph Sferra, MD, of ProMedica Health System in Toledo, Ohio, and colleagues.

Tumor size and tumor stage - both of which tended to be greater in women insured by Medicaid—were independent predictors of receiving mastectomy, the researchers reported online in JAMA Surgery.

“Early detection efforts, such as increasing the rate of screening mammography among Medicaid patients, could increase the number of patients who receive breast-conserving treatment,” they wrote.

An NIH consensus statement released in 1991 indicated a preference for breast-conserving treatment over mastectomy when surgery was performed for early-stage breast cancer. That was backed by evidence from randomized trials showing comparable survival rates using the two approaches. Mastectomy remains a common treatment in early-stage breast cancer, however, with reported rates up to 30% for stage I disease and 82% for stage III disease. To explore the effect of insurance status on the choice of surgical treatment, Sferra and colleagues performed a retrospective analysis of data from 1,539 women who underwent surgery at ProMedica for stage I to III invasive breast cancer from 1996 through 2009. Overall, 42% of the women had a mastectomy and the rest had breast-conserving surgery. At presentation, tumor size was significantly greater among women insured by Medicaid than among those with private insurance (3.3 versus 2.1 cm, P<0.05). And the percentage of patients who presented with stage I tumors was lower in the Medicaid group (30% versus 47%, P<0.05). Both findings are consistent with previous studies showing that women with Medicaid typically present with later-stage disease. Overall, breast-conserving surgery was the treatment chosen by the majority of women with tumors less than 2 cm (71% versus 29%), whereas mastectomy was chosen by most for tumors 2 to 4 cm (54% versus 46%) and larger than 4 cm (81% versus 19%). The trends were similar when the tumors were broken down by stage. But insurance status came into play, as well. Unlike for larger tumors, for tumors less than 2 cm, patients with Medicaid were less likely to undergo mastectomy compared with women with private insurance (11% versus 47%, P<0.05), which could be related to patient choice or surgeon preference, according to the researchers. "Surgeons are reimbursed 40% less for breast-conserving treatment than for mastectomy," they noted. "Reimbursement does impact what surgery is performed for early-stage breast cancer. Surgeons may not be incentivized appropriately for providing less-invasive procedures of equal efficacy." "Understanding the effect of reimbursement models on the treatment of early-stage breast cancer may reveal targets for overall quality improvement [and] this may mean increasing the number of specialists," they added.