Potential association of prolonged patient interval and advanced anatomic stage in breast cancer patients in the area affected by the 2011 triple disaster in Fukushima, Japan: Retrospective observational study

For five years after the 2011 triple disaster (earthquake, tsunami, and nuclear disaster) in Japan, the proportion of patients with undiagnosed symptomatic breast cancer remained elevated in the coastal area of Fukushima. These individuals experienced a prolonged interval from first symptom recognition to initial medical consultation (hereafter referred to as the patient interval). We aimed to investigate how this prolonged patient interval affected disease staging. Using patient records, we retrospectively extracted females with newly and pathologically diagnosed breast cancer who initially presented to Minamisoma Municipal General Hospital from March 2011 to March 2016. We estimated the proportion with advanced-stage disease (III, IV) according to the patient interval duration (<3 months, 3–12 months, and 12 months plus). A cut-off patient interval value was determined based on the previous evidence with regards to impacts on survival prospects. Logistic regression approaches were used to fulfill the study outcome. The proportion of patients with advanced-stage disease was 10.3% for < 3 months (7/68), 18.2% for 3–12 months (2/11), and 66.7% for more than 12 months (12/18). We found a similar trend using the multivariate logistic regression analyses. Prolongation of the patient interval was associated with advanced-stage disease among female patients with breast cancer.