The cancer drug Herceptin combined with chemotherapy works better than chemotherapy alone in patients with a certain type of advanced or inflammatory breast cancer, doctors said on Friday.

They said the drug, a billion-dollar seller for Swiss drugmaker Roche, was particularly effective for many women with advanced or inflammatory breast cancer because many of them have tumours which overproduce a protein called the human epidermal growth factor receptor-2, or HER2.

Luca Gianni of the National Cancer Institute in Milan, Italy, compared patients with HER2-positive breast cancer treated with chemotherapy and Herceptin combined for one year with patients treated with chemotherapy alone.

Herceptin, also known as trastuzumab, significantly improved event-free survival, he wrote in a study in The Lancet medical journal, with 71 percent of patients treated with the combination surviving for three years without their disease worsening, versus 56 percent who were not given Herceptin.

Locally advanced breast cancers are cases where the tumour has grown to larger than about 5 centimetres across. It accounts for between 6 and 10 percent of new cases of breast cancer and patients have a worse prognosis than those whose tumours are found soon enough to be operated on.

Inflammatory breast cancer is a rare subtype of breast cancer that is particularly aggressive.

While HER2-posaitive tumours account for around 20 percent of all breast cancers, the proportions of locally-advanced and inflammatory breast cancer cases that are HER2-positive are higher - at 35 percent and 40 percent respectively.

“Patients with HER2-positive locally advanced or inflammatory breast cancer are therefore in particular need of effective treatment,” Gianni wrote.

A study published last September found many women are never tested to see if HER2-targeted drugs would work for them, suggesting many breast cancer patients who might benefit from Herceptin were not getting it, while some women taking the drug had never been properly tested.

British drugmaker GlaxoSmithKline Plc also has a medicine for HER2-positive breast cancer called Tykerb.

Breast cancer kills 400,000 women around the world every year and 40,000 in the United States alone.

Many studies have shown a low-fat diet, regular exercise, keeping a lean weight and breastfeeding babies can prevent breast cancer, but a significant percentage of cases are caused by faulty genes and not linked to lifestyle.

By Kate Kelland

LONDON (Reuters)