For some women who've had breast cancer, life after treatment can be just as challenging as life was during treatment. A new study illuminates one of the key reasons for many: 70 percent of women who had breast cancer said they also had problems in the bedroom.

"Its a very high number," said study researcher Dr. Robin Bell. It is well agreed-upon that sexual dysfunction is not unusual among women in this age group, and estimates of its prevalence vary widely, she said, but 70 percent is certainly higher than what would be expected in women of this age.

The results were based on a study of about 1,000 women in Australia who had been diagnosed with invasive breast cancer about two years prior to answering questions about their breast cancer treatment and their sex lives. The average age of women in the study was 54, and all had a romantic partner.

Eighty-two percent of these women said they were happy with their sex lives before their diagnosis, but after treatment they reported a loss of libido and vaginal dryness, Bell said.

The researchers also found that women who had taken certain breast cancer drugs, called aromatase inhibitors, were more likely to report having problems then women who weren't taking them.

Women with breast cancer that is hormone-receptor positive — meaning the cancer grows when fed by female hormones — typically take either an aromatase inhibitor or a drug called tamoxifen, Bell said, both of which are designed to block the hormones from feeding the tumor.

The study found that the women taking the aromatase inhibitors were more likely to report sexual difficulties than those taking tamoxifen.

"Both treatments are highly effective," Bell said, adding that choosing between treatments may come down to quality of life issues.

"This was a good study with a sufficiently large sample of women," said Dr. Patricia Ganz, director of cancer prevention and control research at the University of California at Los Angeles Jonsson Comprehensive Cancer Center.

The results are in line with those of previous studies that have also shown sexual difficulties to be a common problem among women who've had breast cancer, said Ganz, who was not involved with the Australian research. But the new findings suggest aromatase inhibitors may be making things worse.

Still, the study didn't take into account whether women who were post-menopausal had become post-menopausal naturally as they aged or as a result of chemotherapy treatments. It's very common, Ganz said, for women whose menopause was caused by chemotherapy to have more severe symptoms than other women, because the body does not adjust over time, as it does with natural menopause.

"The idea that women who have sexual difficulties after breast cancer is not new," Ganz said, but this study shows that the problem has not gone away. The women in the study were undoubtedly cared for in high-quality health-care facilities by competent physicians who know how to manage vaginal dryness and other sexual difficulties.

Physicians need to ask patients about their sex lives, Ganz said.

"Doctors often don't ask," she said, "And if you don't ask, patients won't tell you."

This article was provided by MyHealthNewsDaily, a sister site to LiveScience.