WASHINGTON, Aug. 21 (UPI) — A new study found that younger women and black women have a greater chance of being diagnosed with ductal carcinoma in situ, or DCIS, however increased diagnosis and treatment of women with cancerous cells has not resulted in statistically significant lower levels of death.
With the discovery that treatment of very early stage cancers has not reduced mortality from the disease significantly, some researchers are questioning the effects of what they describe as over-diagnosis and over-treatment.
“The reason for the decline may be better distinction between DCIS and invasive cancer, but overdiagnosis is likely, given that the incidence of DCIS has increased dramatically over the same period,” researchers wrote in the study, published in JAMA Oncology. “It is unlikely that the decline in mortality is due to more effective treatments because we show here that mortality rates did not vary with specific treatment.”
DCIS, often referred to as stage 0 cancer, is often confined to milk ducts in the breast. With better technology and more screening that more cases are being discovered, however researchers were unsure that greater incidence of treatment is saving lives.
Researchers looked at records for more than 108,196 women collected as part of the Suveillance, Epidemiology, and End Results, or SEER, database to compare the rates of death from breast cancer after a DCIS diagnosis to those of the general female population. Women in the study were between the ages of 15 and 69, with the average amount of time between initial survey and follow-up at about 7 and a half years.
The 20-year mortality rate for breast cancer among women in the study was 3.3 percent. The death rate was higher for women who’d been diagnosed before age 35 — 4.6 percent higher than for older women, and was 4 percent higher for black women than for non-Hispanic white women.
The researchers also found that while lumpectomy and radiotherapy reduced return of invasive cancers for at least 10 years after treatment, the treatments did not reduce overall breast cancer deaths at 20 years as they remained stagnant at 3.3 percent. The number, researchers said, was similar to that of women who’d not been diagnosed with early stage breast cancer.
In a commentary published in JAMA Oncology with the new study, experts write that DCIS once made up about 3 percent of all diagnosed cancers. That number has now ballooned to 20 to 25 percent of diagnoses and, as a result of their looking like invasive cancer pathologically and molecularly, are treated much more proactively than may be necessary.
“Long-term epidemiology studies have demonstrated that the removal of 50,000 to 60,000 DCIS lesions annually has not been accompanied by a reduction in the incidence of invasive breast cancers,” experts wrote in the commentary. “This is in contrast to the experience with removal of colonic polyps and intraepithelial neoplasia lesions of the cervix, in which the removal of precursor lesions has led to a decrease in the incidence of colon and cervical cancer, respectively. We now know that breast cancer encompasses a range of behaviors, from aggressive to indolent; the latter are more likely to surface with screening. The analysis of Narod et al fuels a growing concern that we should rethink our strategy for the detection and treatment of DCIS.”
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