Non-invasive breast cancer, also known as ductal carcinoma in situ, or DCIS, is highly curable. It is most commonly detected on a screening mammogram. The standard of care is surgical removal, followed by breast radiation therapy, in women who wish to conserve their breast. The alternative is a mastectomy. Both modalities have equal survival outcomes. However, there has been a great deal of controversy about the necessity for radiation therapy for DCIS in women who opt for breast conservation.

Proponents for radiation therapy underscore the fact that the risk of a recurrence in the breast can be a more aggressive or even an invasive recurrence. Half of these recurrences are due to invasive breast cancer. The latter has the potential to spread to lymph nodes of the underarm and to other parts of the body. Without radiation therapy, the risk of a local recurrence is approximately 20%. By adding radiation therapy, the risk of such a failure is reduced by half. Needless to say, this is a substantial benefit.

The experts who do not support the routine use of radiation therapy for DCIS espouse that there is no difference in long-term survival between women who undergo radiation therapy versus those who do not. A woman who is willing to accept the higher risk of a recurrence in the breast may be treated with surgical removal alone. The question then arises: which women with DCIS should undergo radiation therapy and which should be observed?

Since the potential common side effects from radiation therapy, such as a skin reaction and fatigue, are temporary and the woman’s risk for developing an invasive and potentially life threatening breast recurrence is significant, it is prudent for women to take the more aggressive approach.

Certain factors, such as the woman’s age, her overall health, the surgical margin (or rim of normal breast tissue removed around the DCIS, with the wider the margin being more favorable), and the grade of the DCIS (low grade is much less aggressive than high grade and intermediate grade falls between these two extremes), should factor into the decision making.

Radiation therapy should be strongly considered for young women, women who have close margins, women with DCIS measuring more than ½ centimeter (cm) and/or those do not have low grade DCIS. On the other hand, studies show that even older women with DCIS measuring less than ½ cm, who have wide margins and/or low grade DCIS, benefit from the addition of radiation therapy.

The good news is that radiation therapy is a very easy, painless treatment that can enable women with DCIS to be at low risk of having the disease return in the treated breast, and peace of mind that they left no stone unturned.