Radiation Reduces Recurrences of Ductal Carcinoma in Situ of the Breast

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According to a recent article published in The Lancet, results from a clinical trial provide confirmatory evidence that radiation following the surgical removal of cancer reduces the rate of recurrences in ductal carcinoma in situ of the breast.

Ductal carcinoma in situ (DCIS) is the earliest possible clinical diagnosis of breast cancer and is frequently diagnosed with screening mammography that has detected small areas of calcification in the breast. Patients rarely suspect that they have breast cancer with this stage cancer. It is estimated that the average time to develop invasive breast cancer from DCIS is 5-8 years. DCIS can be thought of as a pre-cancerous or early stage growth of abnormal cells in the ducts of the breast. Historically, DCIS was an extremely uncommon finding in women and little attention was given to defining its optimal treatment. This is because DCIS can be cured almost 100% of the time with a surgical mastectomy (complete removal of the breast). With the increased use of screening mammography, women are more likely to have cancer diagnosed at an earlier stage, and therefore, the number of women diagnosed with DCIS is increasing. If DCIS is untreated, approximately 30% of patients will develop invasive breast cancer an average of 10 years from the initial diagnosis.

Although nearly all cases of DCIS can be cured following a mastectomy, most patients opt for a less aggressive type of surgery called a lumpectomy, in which only the cancer and a small margin of normal tissue are removed. However, this leaves some patients susceptible to a cancer recurrence, as all of the cancer cells may not have been removed during surgery and were not detectable in the body at that time. In more advanced, yet still localized stages of breast cancer, surgery is followed by radiation therapy in order to significantly reduce the risk of a cancer recurrence. Furthermore, patients who test positive for having a type of cancer called hormone-positive cancer, in which cancer cells are stimulated to grow from certain female hormones, are treated with agents to prevent or reduce the growth stimulatory effects of female hormones on cancer cells. Nolvadex ® (tamoxifen) is the most commonly used hormone agent, while aromatase inhibitors are beginning to become more commonly prescribed in order to reduce cancer recurrences.

Recently, researchers from England, Australia and New Zealand conducted a clinical trial to evaluate the risks and benefits of radiation, Nolvadex ®, or both following surgery in the treatment of DCIS of the breast. This trial involved over 1,700 women diagnosed with DCIS who were treated with either radiation, Nolvadex ®, radiation plus Nolvadex ® or no further treatment following the complete surgical removal of their cancer and were directly compared. Approximately 4 1/2 years following therapy, the highest rate of cancer recurrences occurred in the group of women treated with surgery only (22%), followed by those treated with surgery plus Nolvadex ® (18%), surgery plus radiation (8%) and surgery plus radiation and Nolvadex ® (6%). Among all of the women in this trial, 8 were subsequently diagnosed with tumors of gynecological origin, 7 of whom had received treatment with Nolvadex ®.

The researchers concluded that these results provide more evidence indicating that radiation following surgery reduces the rate of cancer recurrences in women diagnosed with DCIS of the breast. In this trial, the use of Nolvadex ® did not appear to provide any protective effect against cancer recurrences and may have contributed to subsequent gynecologic tumors. These results are in contrast with results from previous trials indicating a benefit from the use of Nolvadex ® in women with hormone-positive DCIS. The researchers stated that longer follow up is necessary to determine if any treatment provided a clear survival benefit or if radiation therapy led to any long-term adverse medical effects. Patients diagnosed with DCIS may wish to speak with their physician about the risks and benefits of therapy with radiation and/or Nolvadex ® following surgery.

Reference: UK Coordinating Committee on Cancer Research (UKCCCR) Ductal Carcinoma in Situ (DCIS) Working Party on Behalf of DCIS Trialists in the UK, Austaralia, and New Zealand. The Lancet. 2003;362:95-102.