Young onset breast cancer in Southern China - a 5-year clinico-pathological study from a multi-centre database

Breast cancer onset is known to be younger in China when compared to many westernized countries, the reason remains unknown. This study aims to evaluate the clinical and pathological characteristics of young breast cancer in Hong Kong and Shenzhen, China.

This is a 5-year retrospective review of a prospectively-maintained region-wide database. Patients treated in Hong Kong and Shenzhen between 2013 and 2017 were analysed.

1610 breast cancer patients were identified for analysis, 1108 patients were from Hong Kong and 502 patients were from Shenzhen. Median age of breast cancer onset was 60 years old in Hong Kong (Range 21 - 103), while that in Shenzhen was 46 years old (Range 23 - 85). 59 (5.3%) patients from the Hong Kong cohort were younger than 40 years old at the age of diagnosis (i.e. young breast cancer), comparing to 152 (30.3%) patients from the Shenzhen cohort (p < 0.0001). There were more nulliparity, positive family history and use of exogenous hormones in young breast cancer patients in Hong Kong (p = 0.0043, < 0.0001 and 0.0022). Pathological characteristics were however comparable between the two cohorts, apart from being more triple negative breast cancers in young breast cancer patients in Hong Kong (p = 0.05).

Age of onset of breast cancer tends to be younger in mainland China than in Hong Kong. Personal and familial risk factors were not significantly different. Environmental factor may play an important role.