Women with DCIS have lower all-cause mortality than general population
Women above 50 years of age with ductal carcinoma in situ (DCIS) have a lower risk of all-cause mortality at 10 years compared with the general population, new data presented at the European Cancer Congress 2017 (ECCO2017) have shown.
The data, from 9,799 Dutch women treated for DCIS, also showed a low absolute risk of breast cancer-specific mortality at 15 years. [ECCO 2017, abstract 173]
“Women in the nationwide cohort received DCIS treatment by surgery with or without radiotherapy between 1989 and 2004. After a median follow-up of 10 years, their risk of dying from any cause was 10 percent lower than expected mortality rates in the general female population [standardized mortality ratio (SMR), 0.9],” reported Dr Lotte Elshof of the Netherlands Cancer Institute.
Eighty percent of women in the cohort were older than 50 years of age, and the median age was 57 years. Among 1,429 deaths that occurred during the follow-up period, 368 (4 percent) were due to cardiovascular disease and 284 (3 percent) were due to breast cancer.
The women with DCIS had lower risks of death from diseases of the circulatory, respiratory and digestive system (SMR, 0.8, 0.7 and 0.7, respectively), mental and behavioural disorders (SMR, 0.7), as well as endocrine, nutritional and metabolic diseases (SMR, 0.7).
The risk of breast cancer death was higher in the DCIS cohort (SMR, 3.3), but the risks of mortality from lung and urogenital cancers were lower compared with the general female population (SMR, 0.7 and 0.6, respectively).
“At 15 years, the cumulative breast cancer-specific mortality rate was low, at 3.9 percent,” said Elshof. “For women treated for DCIS alone, the risk of dying from breast cancer was only slightly higher than that in the general population.”
“We also showed that for women with DCIS, the risk of dying from breast cancer decreases with increasing age. The SMR for breast cancer-specific mortality decreased from 23.2 for women below 40 years of age to 1.9 for women above 75 years of age,” Elshof continued.
In patients who subsequently developed invasive breast cancer, however, breast cancer-specific mortality was much higher than in patients who did not develop invasive breast cancer (SMR, 26.6 vs 2).
“Our findings suggest that a history of primary DCIS has no negative impact on overall survival,” said Elshof. “It might seem surprising that women with DCIS actually have a lower mortality rate than the general population. However, the vast majority of DCIS cases would have been diagnosed via breast screening, which suggests that these women may be health-conscious and well enough to participate in screening.”
The researchers will collaborate with centres in the UK and US to expand the study and identify factors that contribute to DCIS progression into invasive breast cancer.