Long-term tamoxifen use linked to rise in second breast cancer, study finds

A new study suggests long-term use of tamoxifen is linked to increased risk of developing an aggressive type of breast cancer, but experts say the drug’s proven track record in reducing risk of both recurrence of the disease and death outweigh potential negative effects.

TORONTO — A new study suggests long-term use of tamoxifen is linked to increased risk of developing an aggressive type of breast cancer, but experts say the drug’s proven track record in reducing risk of both recurrence of the disease and death outweigh potential negative effects.

Researchers from Fred Hutchinson Cancer Research Center in Seattle looked at 728 women who had been diagnosed with breast cancer. Those women were compared to 367 others diagnosed with both a first and second breast cancer.

A second breast cancer can mean a tumour occurring in the opposite breast or when two separate tumours develop in the same breast.

The main finding from the study, published online Tuesday in the journal Cancer Research, was that tamoxifen lowered the risk of any second breast cancer overall by about half, said lead author Dr. Christopher Li.

While long-term use of the drug for five or more years reduced the more common type of breast cancer by about 60 per cent, it also increased the risk of a more aggressive subtype of the disease by more than 400 per cent, Li said.

Tamoxifen is an estrogen-blocking drug. Li said such drugs were specifically designed to block the estrogen receptor to prevent the growth of breast cancer cells. But not all breast cancers have the estrogen receptor (ER), Li said. Those that don’t tend to be more aggressive and to spread more quickly.

“For the estrogen receptor-positive cancer, we have targeted therapy that again has been proven to again reduce mortality,” said Li. “That’s one of the reasons why ER-negative cancers are more worrisome because we don’t have a targeted treatment for them.”

Li said it’s important to remember that any treatment has risks and benefits associated with it, and tamoxifen is no exception.

Tamoxifen lowers breast cancer patients’ risk of dying of the disease, and has also been shown to lower a woman’s risk of developing a recurrent breast cancer and a second breast cancer, he noted. But use of tamoxifen also comes with risk of stroke, as well as the risk of endometrial cancer, he added.

“So here we’re finding that we’re adding potentially another risk to the risk-benefit equation,” Li said. “We’re finding that there is this increased risk in this more aggressive subtype of second breast cancer. However, we also overall found using tamoxifen did lower the risk of any type of second breast cancer overall.”

“For that reason, we don’t really think that this study changes the overall risk-benefit equation because the benefits for most women who are eligible to use this treatment are going to still outweigh the risks.”

Dr. Pamela Goodwin, head of the medical breast program at Toronto’s Princess Margaret Hospital, said there is a net benefit in using tamoxifen, with decreased risks of death, recurrence of the disease and cancer spreading to the other breast.

Just Posted

Person airlifted to hospital after collision near Innisfail

One person was airlifted to hospital after a serious collision west of… Continue reading

Sunny weather improves farmers’ prospects

A harvester kicking up dust. It’s a picture that will bring a… Continue reading

Rural transit pilot project being considered

Penhold, Innisfail and Red Deer County councils to decide whether to go ahead with project

Red Deer fire station up for sale

Home sweet home at Fire Station 4

‘Stupid’ law preventing Canada’s re-engagement with Iran: retired envoy

OTTAWA — The real reason the Liberal government hasn’t been able to… Continue reading

Voters head to polls for BC municipal elections today

VANCOUVER — Voters in British Columbia will head to the polls today… Continue reading

All sharks tagged in N.S. expedition can now be tracked on Ocearch website

HALIFAX — All six of the sharks tagged in Nova Scotian waters… Continue reading

Memorial service for former PQ minister Lise Payette today in Montreal

MONTREAL — Mourners will gather to remember former Parti Quebecois cabinet minister… Continue reading

Immunotherapy scores a first win against some breast cancers

For the first time, one of the new immunotherapy drugs has shown… Continue reading

‘Mom I’m in trouble:’ Canadian, Brit face 10 years in jail for alleged graffiti

GRANDE PRAIRIE, Alta. — The mother of a Canadian who was arrested… Continue reading

Coyote on the prowl near Penhold

This coyote was out on the prowl in a field just west… Continue reading

Most Read