Tumors caught early have a lower probability of advancing to the lymph nodes and improve patient outcomes, the BMJ study found.
Awareness on the importance of breast cancer screening is widespread, both in the United States and globally. Per the US Preventive Services Task Force, women 50 to 74 years of age are recommended to start biennial screening mammography. This could be one of the reasons for the significantly improved 5-year breast cancer survival rates in the United States: from 75% back in the 1970s to 90% in the 2000s. Now, a study from the Netherlands has provided proof of the impact of screening and early diagnosis.
Researchers in Netherlands conducted an exhaustive, nationwide population study, investigating their national cancer registry, which included nearly 174,000 patients with breast cancer. The women, diagnosed with primary breast cancer between 1999 and 2012, were placed in 1 of 2 cohorts based on whether they were diagnosed between 1999 and 2005 or between 2006 and 2012. The primary outcome measure was survival.
Women diagnosed in the later years (after 2006) had relatively smaller tumors that, most often, did not present with lymph node metastases. These patients did receive more chemotherapy, hormonal therapy, and targeted therapy compared with those diagnosed before 2006. The relative 5-year survival rate in the 2006 to 2012 cohort was 96%, and 100% if the tumors were less than 1 cm in size. Mortality in both cohorts correlated with increasing tumor size. Additionally, the authors found that mortality in patients with invasive disease did not increase till the tumors reached 1 cm in size or till the cancer progressed to the lymph nodes.
Between 1999 and 2012, the authors observed a 17% increase in the diagnosis of breast cancer, which they attribute to the ageing population—older age being a major risk factor for breast cancer.
The authors believe that their study can help both policymakers and physicians in clinical decision making, while raising patient awareness on the impact of stage and treatment choices on disease prognosis.