A successful fight against breast cancer might seem on some days a pyrrhic victory, particularly as nearly one-third of survivors remain jobless several years after their careers had been interrupted.

Though previous studies had placed the U.S. unemployment rate for breast cancer survivors at 20 percent, new research published Sunday in the journal Cancer finds that nearly one-third of such women remain unemployed four years after treatment. The highest unemployment rates are among those who received chemotherapy, say researchers from the University of Michigan Comprehensive Cancer Center.

Reshma Jagsi, a professor of radiation oncology, led a team surveying women in Detroit and Los Angeles who had received diagnoses for early stage breast cancer. They focussed on 746 of the women who had reported employment, surveying them again nine months after diagnosis, with a follow-up several years later.

"Many doctors believe that even though patients may miss work during treatment, they will 'bounce back' in the longer term,” Jagsi said in a university press release. “The results of this study suggest otherwise. Loss of employment is a possible long-term negative consequence of chemotherapy that may not have been fully appreciated to date.”

Among those unemployed breast cancer survivors, 39 percent reported they were actively searching for work while 55 percent said they wanted to work. Naturally, the breast cancer survivors who remained unemployed also reported the worst personal finances. Jagsi and her colleagues say unemployment may represent a long-term problem for breast cancer survivors who often require lengthy periods of convalescence during treatment, straining their connections to the working world.

Additionally, chemotherapy often causes long-term side effects such as neuropathy or cognitive problems, which may also dim job prospects in a job market still recovering since the last economic recession. Jagsi said oncologists and other clinicians must strive to reduce the burden of breast cancer while also developing strategies to identify those patients less likely to benefit from chemotherapy, thus saving them the pain and aggravation.

Many patients take time off of work during chemotherapy treatment to deal with the immediate side effects of the therapy. The researchers say it's possible this may lead to long-term employment problems. In addition, chemotherapy treatments can cause long-term side effects such as neuropathy or cognitive issues, which might also affect job prospects.

The findings point to the need to reduce the burden of breast cancer treatment, and reinforce current efforts to develop better strategies for identifying patients less likely to benefit from chemotherapy.

A similar study of nearly 15,000 Danish women published in January found only a 10 percent unemployment rate for breast cancer survivors two years after treatment, finding that adjuvant therapy didn’t affect employment rates following treatment. Those researchers found that socioeconomic factors, along with the country’s demography, tended to most influence employment rates for breast cancer survivors.

According to the American Cancer Society, some 235,030 Americans will receive breast cancer diagnoses this year, while 40,430 will die.

Source: Carlsen, K., Ewertz, M., Dalton, S.O. Unemployment among breast cancer survivors. Journal of Scandinavian Journal of Public Health. 2014.