Besides breast cancer, women who drank lightly on a daily basis also experienced higher rates of cancers relating to the liver, bowel, mouth, throat, esophagus and larynx.

Ductal carcinoma in situ (DCIS, or stage 0 breast cancer) accounts for approximately 20% of breast cancers detected by a mammogram.

In some cases, pathologists look at only a small amount of tumor, Dr. Morrow said, and could have missed areas of invasive cancer.

Many of these women would often choose to undergo either a mastectomy, lumpectomy, or even double mastectomy, which effectively removes a healthy breast out of fear of developing the dreaded disease.

A new study published by the British Medical Journal showed that light drinking, which was defined as up to one drink a day for women and two a day for men, was shown to only slightly increase the risk of cancer across the board.

But women who reportedly consumed a glass of wine per day for 30 days in a row had a 13 percent higher risk of overall cancer regardless whether they were or not smokers. In patients who underwent lumpectomy, radiotherapy was associated with a lower risk of ipsilateral invasive recurrence but not breast cancer-specific mortality at 10 years.

“At this time, the decision about whether or not to have surgery for DCIS has to be made by a woman and her doctors considering all known risk factors, the type of DCIS and personal preferences concerning future screening”, Porter said.

An important exception must be emphasized: The study found that death rates were indeed higher for certain women with DCIS, including African Americans and those who were younger than 40 when diagnosed. But researchers discovered that the rate of dying from breast cancer within 20 years was the same for all three groups – 3.3 percent – which is similar to that of the general population. These rates, however, were still lower than those for women with more invasive stages of breast cancer. Cancer that spreads into the rest of the breast or beyond is considered invasive.

The study involved more than 100,000 women and they were followed for more than two decades. Today, WCH is a world leader in the health of women and Canada’s leading, academic ambulatory hospital. Thus, more aggressive treatment of DCIS does not necessarily reduce breast cancer mortality.

The report’s findings “provide a compelling case that it is time for change”, wrote Dr. Laura Esserman, a surgeon and breast cancer oncology specialist at University of California, San Francisco. “We’ve always had a sense that perhaps we were over-treating DCIS”, Maggie DiNome, MD, director of the Margie Petersen Breast Center at John Wayne Cancer Institute at Providence Saint John’s Health Center in Santa Monica, Calif., tells Yahoo Health.