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Four years ago, chemotherapy treatments thrust Carys Cao into early menopause – a devastating side effect she hadn’t expected when fighting breast cancer. (Kevin Van Paassen For The Globe and Mail)
Four years ago, chemotherapy treatments thrust Carys Cao into early menopause – a devastating side effect she hadn’t expected when fighting breast cancer. (Kevin Van Paassen For The Globe and Mail)

Putting ovaries to sleep: The fight for fertility for breast cancer patients Add to ...

When Carys Cao was 32, she found a lump in her breast the size of a lima bean. By the time a specialist confirmed she had breast cancer, almost four months later, the lump had grown by more than a centimetre.

Cao, now 36, said her surgical oncologist called it “an angry cancer.” But no one informed her that chemotherapy could affect her fertility until two weeks before she began treatment, she said. After frantic calls to fertility specialists, Cao discovered she had missed the window to have her eggs retrieved and frozen without fertility drugs, which could stimulate her cancer growth. She recalls sobbing as she told her husband of nine years that they were unlikely to ever conceive.

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Then, partway through treatment, Cao began to suffer from what she thought were high fevers. A specialist told her she was having hot flashes – and that chemo had put her body into premature menopause. Though she is now cancer-free, Cao continues to suffer from menopause symptoms, including decreased sex drive, depression, achiness and fatigue, and takes medication for joint pain. “I feel like an old person,” she said.

Premature menopause is a common side effect of chemotherapy, which can shut down estrogen production by destroying a woman’s egg supply.

Compared with natural menopause, which occurs gradually over a period of 10 to 20 years, chemotherapy-induced menopause can feel more intense, jolting young women into night sweats, weight gain, thinning hair, dry skin, loss of breast fullness and bone loss.

A study, however, suggests chemotherapy-induced menopause may be preventable: Researchers have found that a drug called goserelin may protect younger patients with certain forms of breast cancer from going into early menopause – and increase their chances of conceiving after chemotherapy.

The drug works by putting a woman’s ovaries into temporary hibernation during chemotherapy, “so there’s no further damage to the eggs,” said Dr. Kathy Albain, senior author of a study presented at the annual meeting of the American Society of Clinical Oncology last month.

The experimental treatment has potential to reduce the risk of ovarian failure as a result of chemotherapy for hundreds of Canadians with breast cancer, depending on which type they have. Of 22,700 new cases of breast cancer in Canada each year, roughly one in five occurs in women age 50 and under.

For patients under age 50, Albain said, premature menopause can be one of the most agonizing side effects of chemotherapy. “Sometimes women tell me the chemotherapy wasn’t as bad as dealing with sudden menopause.”

Cao said she’ll never forget her first hot flash, when her temperature shot up to 102 F. “I was dizzy and completely out of it,” she said. “It was the worst fever of my entire life.”

For the goserelin study, researchers assigned 257 patients under age 50 to receive either chemotherapy or chemotherapy plus goserelin, a drug approved to treat prostate cancer, certain gynecological disorders and some forms of breast cancer.

After two years, 22 per cent of women who received chemotherapy alone had stopped menstruating and had a marker of reduced estrogen production. But just 8 per cent of patients who had goserelin in addition to chemotherapy had these clinical signs of menopause.

The researchers found that goserelin may help preserve fertility as well. Within two years of chemotherapy, 21 per cent of patients in the goserelin group had a pregnancy, compared with 11 per cent in the chemotherapy-only group.

Nevertheless, Albain emphasized that younger patients who are determined to conceive should consider such options as egg freezing prior to chemotherapy. Despite the study results, she said, “you can’t say this approach is foolproof.”

Women in the goserelin group received a monthly injection of the drug – worth $600 (U.S.) – for the duration of a four- to six-month course of chemotherapy. Side effects of goserelin were minimal, other than symptoms such as hot flashes resulting from the temporary suppression of ovarian function, Albain said.

All patients in the study had hormone-receptor-negative breast cancers, meaning their cancer cells did not have specific proteins that pick up hormone signals that trigger cell growth.

Dr. Vanessa Bernstein, a medical oncologist and spokesperson for the BC Cancer Agency, said the findings are promising, but do not apply to women with hormone-sensitive breast cancers, which account for more than half of patients under age 50.

Bernstein, who attended the study’s presentation in Chicago, said the number of study participants was small and data on some patients were missing at the two-year endpoints. Nevertheless, “I think it’s a good study,” she said.

Based on the drug’s safety profile and success rate in preserving fertility, Bernstein said she would feel comfortable prescribing goserelin to younger patients with hormone-receptor-negative breast cancers who hope to get pregnant after chemotherapy. “We could offer it to women as a way of preserving ovarian function,” she said.

Although the drug is approved in Canada for other uses, goserelin would not be covered for the experimental treatment by provincial health plans. Nevertheless, the study is a “promising development” for younger patients, said MJ DeCoteau, executive director of Rethink Breast Cancer, a Toronto-based organization that supports young women with breast cancer.

Long after patients are cancer-free, premature menopause can wreak havoc on their physical and emotional well-being, DeCoteau said.

“We tend to think about losing a breast, the radical surgeries,” she said, “but the [risk of] early menopause is something that many people out there don’t know about.”

Follow on Twitter: @AdrianaBarton

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