Scientists reported promising gains for treating colorectal cancer that has spread to the liver, showing that chemotherapy before and after surgery to remove liver tumors can help keep the disease in check.

The study is the first to scientifically test an approach that many doctors have tried for patients with advanced colon and rectal cancers.

"It justifies what some of us have already been doing" and shows that aggressively treating patients with limited spread of colorectal cancer is reasonable, said Dr Jeffrey Meyerhardt, a cancer specialist at Dana Farber Cancer Institute in Boston.

About 1 million people worldwide develop colorectal cancer each year, including more than 150,000 in the US, where it is the third most common major cancer. In up to half of all patients, the disease spreads after initial treatment to the liver. For many cancers, spread to the liver means the disease has also spread elsewhere, is incurable and surgery is not an option.

But with colorectal cancer, sometimes the disease spreads only to the liver, and surgery to remove these growths increasingly is being attempted, said Dr Neal Meropol, director of the gastrointestinal cancer programme at Fox Chase Cancer Center in Philadelphia. Even so, recurrence is common, and only about 30 per cent of patients who have this surgery survive five years.

In the new study, 42 per cent of patients who got chemotherapy before and after the liver surgery had no recurrence after an average of four years, versus 33 per cent of patients who had surgery alone. The good results mean the approach could become standard treatment for these patients, said Dr Bernard Nordlinger, the lead author and a cancer specialist at Ambroise Pare Hospital in Paris.