According to recent studies, ductal carcinoma in situ, a non-invasive benign tumour of the breast, is over-diagnosed and therefore overtreated. An unfortunate reaction to overtreatment of benign breast tumours might be a decrease of the active surveillance of the breast tissue which causes patients to be underdiagnosed for invasive ductal carcinoma.
Tumours can either be benign or malignant. Benign tumours are mild, localised and are non-invasive. A primary identification factor of a benign tumour is that the cells of a tumour remain similar to the cells of the originating organ. Malignant tumours can be extremely invasive as they invade blood vessels and travel through the blood to reach secondary organs further away from the origin where they form secondary tumours. The invasiveness of cancer can be classified into low grade, middle grade, and high grade. Active surveillance is a method of monitoring changes in the cells of an organ that may have the potential of becoming malignant through regular testing.
Widespread mammography has resulted in the widespread overdiagnosis of ductal carcinoma in situ. It is unclear exactly how many cases of ductal carcinoma in situ are the result of overdiagnosis, but some estimates place the number as many as 30% of new cases. Overdiagnosis leads to overtreatment. To avoid overtreatment, some recommendations have suggested a technique called “active surveillance” of breast tissue with a diagnosis of ductal carcinoma in situ, in which treatment only begins once there is an indication that a tumour is spreading. Active surveillance, of course, comes with the risk of underestimating the incidences of invasive ductal carcinoma.
Factors of Decreasing Surveillance
A study was conducted by the Division of Surgical Oncology of Loma Linda University in California where authors de Paz Villanueva, Carlos Chavez, and their colleagues sought to find out the factors associated with the underestimation of invasive ductal carcinoma in patients undergoing active surveillance. To do this, he and his colleagues conducted a retrospective study of female patients who had a clinical diagnosis of non–high-grade ductal carcinoma in situ and underwent definitive surgical treatment. The study data was retrieved from the National Cancer Database, where researchers isolated data between the time periods of January 1, 1998, to December 31, 2012.
The results of this study were published in JAMA Surgery. The researchers found that 22.2% of those with presenting with non-high grade ductal carcinoma in situ were actually found to have invasive ductal carcinoma at surgery. Four factors were associated with the presence of invasive ductal carcinoma in women with an initial benign diagnosis. These factors were younger age, negative estrogen receptor status, treatment in an academic facility, and higher annual income.
Doctors Urged to Take Active Surveillance
These numbers are quite high and urge doctors to take active surveillance into consideration even after surgery for non-high-grade ductal carcinoma in situ breast cancer to avoid the possibility of overlooking the diagnosis for a malignant growth and offering the patient early treatment to prevent complications. These methods should primarily be considered for the diagnosis of invasive ductal carcinoma in situ women who have risk factors for malignant cancers.These sociodemographic risk factors need to be acknowledged by health professionals and taken into consideration when selecting patients for active surveillance, instead of aggressive therapy.
Written by Dr. Apollina Sharma, MBBS, GradDip EXMD
de Paz Villanueva, Carlos Chavez, et al. “Factors Associated with Underestimation of Invasive Cancer in Patients with Ductal Carcinoma in Situ: Precautions for Active Surveillance.” JAMA surgery.