Screening has led to more cases of DCIS being diagnosed

The findings of doctors at a Glasgow hospital are published in this week's edition of the medical journal The Lancet.

The research was carried out by David George and colleagues at the Western Infirmary.

They looked at the treatment of 1,700 women in the UK, Australia and New Zealand after they were diagnosed with ductal carcinoma in situ (DCIS).

This is early breast cancer, where the cancer cells are contained within the milk ducts and have not spread into the surrounding tissue.

Breast screening has led to an increasing diagnosis of the condition, which is almost always completely cured.

Too drastic

However, the treatment has been the subject of controversy.

Mastectomy is often considered to be too drastic for DCIS, but some believe it is not enough to remove the duct without additional treatment.

Mr George and his colleagues investigated whether additional treatment with radiotherapy, medication or a combination of both could reduce recurrence of breast cancer after surgery.

Many surgeons, especially in the UK, think that radiotherapy is not required if the disease is completely removed in surgery Joan Houghton Co-author

They said that radiotherapy after surgery reduced the relative risk of recurrence in the same breast by more than 60%.

It also cut the overall relative risk of invasive cancer in the same breast by more than half.

The use of anti-oestrogen drug Tamoxifen led to a 30% fall in the risk of DCIS recurring, but had no effect in reducing the risk of invasive cancer in the same breast.

Neither treatment had any effect on the cancer risk in the other breast.

Co-author Joan Houghton said: "These results are important because many surgeons, especially in the UK, think that radiotherapy is not required if the disease is completely removed in surgery.