Epidemiology and clinicopathologic features of breast cancer in China and the United States

BACKGROUND: Breast cancer has kept increasing since the past decades and the incidence rate is the highest among all neoplasms nowadays. China, as well as other countries, faces severe burden from the increasing population with breast cancer. This study aimed to analyze the epidemiology and clinicopathologic features of breast cancer in China and the United States (US). METHODS: Data of hospitalized patients diagnosed with primary breast cancer between 1 January 1999 and 31 December 2014 in the Cancer Hospital, Chinese Academy of Medical Sciences (CHCAMS) were reviewed. Clinical and demographic data were extracted from medical history systems, and the sixteen-year trends were analyzed. Meanwhile, retrieved data from the Surveillance, Epidemiology, and End Results (SEER) database from 1999 to 2014 were used for comparisons. RESULTS: A total of 18,768 breast cancer patients were included from CHCAMS, China, with 18,685 female cases (99.57%) and 81 male cases (0.43%). A total of 762,954 breast cancer patients were included from the SEER database, US, with 757,357 female cases (99.27%) and 5,597 male cases (0.73%). The peak age of breast cancer was 45–49 years old from 1999 to 2014 in China, while the peak age was 55–59 years from 1999 to 2006 and 60–64 years from 2007 to 2014 in the US. There were more young (<35 years, 6.56% vs. 1.97%, P<0.001), less elderly (≥65 years, 9.99% vs. 40.88%, P<0.001), less stage I (24.93% vs. 48.84%, P<0.001) and more stage III (21.00% vs. 12.35%, P<0.001) breast cancer patients in China than in the US. Patients aged 30–49 years old had a decreased trend (P<0.001), while 55–64 years old patients had an increased trend (P<0.001) from 1999 to 2014 in China, the same trend was also observed in the US. Mucinous carcinoma and histological grade I breast cancer patients increased with age both in China and the US (P<0.001). CONCLUSIONS: The unique epidemiology and clinicopathologic features of breast cancer (earlier peak age, more younger patients, more advanced stage, etc.), as well as the typical trend in China, should be seriously recognized, so as to guide future prevention and management strategies.