No Evidence of Human Papillomavirus in Patients with Breast Cancer in Hong Kong, Southern China

Several studies have suggested that viral oncogenesis is one of the etiologic factors of breast cancer, while others are provocative, however, their association remains controversial. The purpose of this study was to investigate whether the human papillomavirus (HPV) DNA is present in the blood and tissue samples of breast cancer patients in Hong Kong. A total of 102 patients with breast tumour tissues and adjacent normal tissues were available and recruited unselectively. Both DNA and RNA were extracted from those samples, and real-time quantitative PCR was performed to detect HPV-16, with 18 sequences targeting the E6 and L1 regions. Results showed that HPV DNA sequences were absent in all the blood and breast tissues. These data argue against the role of oncogenic HPV in the pathogenesis of breast cancer. Additional lines of evidence need to be obtained in order to assess the possibility of breast cancer prevention using HPV vaccines. 1. Introduction The incidence of breast cancer in Hong Kong is 1 in 20. Although this is lower than that of Western population, breast cancer is still the most common cancer in Chinese women, and the incidence is rising. Despite decades of research, the etiologic factor(s) for human breast cancer remains unclear. Many studies have identified risk factors such as age, diet, hormonal balance, and genetic predisposition, but a clear underlying cause for the disease has not been established. Emerging evidence suggests that breast cancer most likely is a multifactorial disease consisting of many different causes and factors [1]. Thus, the possibility that a virus is etiologically involved in breast cancer has not been eliminated. Human papilloma virus (HPV) is widely known to be a major instigator for both cervical cancer [2] and a subset of cancers of the head and neck [3]. However, the involvement of the virus in breast cancer remains inconclusive. Previous reports have shown that HPV DNA was detected in breast cancer specimens from diverse populations around the world. The prevalence of HPV positive breast cancer in these studies was reported to vary from 4% to 86% [4]. Although further clarification is required, there have also been promising results in the correlation between breast cancer and HPV [5]. In 2009, Heng et al. [6] substantiated the presence of DNA pertaining to high-risk HPV subtypes 16 and 18 in the specimens of breast cancer cells. Furthermore, Heng et al. found that the oncogenic properties of these HPV-associated breast cancers were comparable to HPV-associated cervical cancer. This evidence suggested a