DCIS Is Often More Invasive Than Thought
By David Douglas
NEW YORK (Reuters Health) - More than one in five patients originally thought to have non-high-grade ductal carcinoma in situ (DCIS) were found to have invasive carcinoma, according to California-based researchers.
The study "corroborates other work that has shown some patients who are considering active surveillance for non-high grade DCIS will indeed already have upstaged disease at the time of their presumed diagnosis of DCIS," Dr. Sharon S. Lum told Reuters Health by email.
In a July 12 online paper in JAMA Surgery, Dr. Lum and colleagues at Loma Linda University School of Medicine report on their analysis of data on more than 37,000 women, ages 40 to 99, who were diagnosed with non-high-grade DCIS between 1998 and 2012.
The women all underwent definitive surgery. Based on final pathological findings, 22.2% had invasive carcinoma at the time of the procedure. These invasive carcinomas were significantly more likely than DCIS to be smaller than one cm and to be of lower grade.
The team also found that being younger was associated with about a 20% greater risk of underestimation of invasive cancer. The odds ratio for 60 to 79 years versus 40 to 49 years was 0.84. For 80 years or older versus 40 to 49 years, it was 0.76. Negative estrogen receptor status was associated with an approximately 60% greater risk of underestimation.
Patients with more comorbidities were also at higher risk of understaging. This amounted to 14% higher odds with one comorbidity and 28% higher with more than one.
Insurance status was not associated with upgrade rates. But treatment at an academic or research center was associated with an up to twofold higher rate of upgrading to invasive cancer compared to treatment at a community cancer program.
Higher income was also significantly associated with an upgraded diagnosis and this "could mirror the higher incidences of breast cancer and mammography screening uptake that have been documented in women of higher income levels."
The investigators observe, "Successful use of active surveillance for patients with DCIS to diminish harmful effects of overtreatment resulting from overdiagnosis will depend on accurate diagnosis and diligent follow-up."
They further point out that in one risk analysis, "the variable with the greatest risk of mortality was understaging invasive cancer at the time of diagnosis."
However, they also cite a study in which five years after breast conservation, only 34% of patients with DCIS underwent annual mammography. And only 15% reported having annual mammography at 10 years.
Given these results the researchers conclude, "When selecting patients for active surveillance of DCIS, factors other than tumor biology associated with invasive carcinoma based on final pathologic findings may need to be considered."
In fact Dr. Lum concluded, "We encourage pursuit of active surveillance of DCIS only in the setting of a clinical trial."
JAMA Surg 2017.
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