Last Updated:  10/25/2009

The information in this column is intended for informational purposes only, and does not constitute medical advice or recommendations by the author.  Please consult with your physician before making any lifestyle or medication changes, or if you have any other concerns regarding your health.

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HPV VIRUS & RISK OF BREAST CANCER

  
The human papilloma virus, or HPV, is already known to directly cause more than 90 percent of all cases of cervical cancer, and this knowledge has been used to develop several HPV vaccines that can dramatically reduce the risk of developing cervical cancer if given to girls and young women before they are exposed to this sexually transmitted virus.   HPV has recently also been linked to an increasing number of cases of oral cancer in patients without the usual risk factors for this cancer (i.e., smoking and increased alcohol intake).

 

Recently, there has been some research evidence suggesting that human papilloma virus (HPV) may also play a role in the development of at least some cases of breast cancer.  However, the data linking breast cancer with chronic HPV infection has been rather contradictory thus far, resulting in a lack of consensus about whether or not HPV actually plays any significant role in breast cancer development.  Now, a newly published research study in the British Journal of Cancer adds more weight to the theory that this cancer-causing (oncogenic) virus may also lead to the development of at least some cases of breast cancer.

 

The authors of this study used two different and complementary tests to evaluate breast tissue specimens for HPV infection.  The researchers tested normal breast tissue from breast biopsies, as well as non-invasive breast cancer (ductal carcinoma in situ, or DCIS) tumors and invasive breast cancer (ductal carcinoma) tumors.  Prior studies looking for evidence of HPV infection within breast cancer cells have relied mostly upon a highly sensitive and sophisticated laboratory test known as reverse transcriptase-polymerase chain reaction (RT-PCR) to identify snippets of HPV DNA.  In these prior studies, HPV DNA has been found to be present, variably, in 25 to 80 percent of tested breast cancer tumors.  However, some experts have questioned the findings of many of these RT-PCR studies, and have suggested that RT-PCR’s notorious susceptibility towards false-positive results (due to contamination) may explain the findings of apparent HPV infection within breast cancer cells.

 

In this new study, the authors not only used RT-PCR, but also microscopic examination of these same breast tissue and breast tumor specimens as well.  As with several other prior studies, this study once again confirmed the presence of cancer-causing (oncogenic) strains of HPV within invasive breast cancer cells, DCIS cells, and normal breast cells.  The authors also tested breast cancer cells growing in cell cultures and, once again, were able to demonstrate HPV DNA in many of these breast cancer cells, using RT-PCR. 

 

In view of the known limitations of RT-PCR, the researchers in this study also evaluated benign and malignant breast cells under a microscope.  To their surprise, they were able to identify the classic changes in these same cells that occur with chronic HPV infection.  (These altered cells, called koilocytes, are considered precancerous when they are identified on Pap smears in women who have chronic HPV infection of the cervix.)  Finally, using antibodies against HPV proteins known to play a role in causing HPV-associated cancers, these researchers were also able to identify traces of this HPV oncoprotein in breast tumor cells and breast tissue as well.    

 

Taken together, the results of this very elegant and complex study appear to show rather convincing evidence of chronic HPV infection in both normal and malignant breast tissue, as well as the characteristic oncogenic HPV-associated changes in the appearance of these cells.  More work still needs to be done to understand the precise role of HPV in breast cancer development, and the incidence of HPV infection within both normal breast tissue and in breast cancer cells.  Although these important questions must first be answered, the findings of this study suggest a potential role for currently available HPV vaccines in the fight against breast cancer. 

 

Disclaimer:  As always, my advice to readers is to seek the advice of your physician before making any significant changes in medications, diet, or level of physical activity

 

Dr. Wascher is an oncologic surgeon, a professor of surgery, a widely published author, and the Physician-in-Chief for Surgical Oncology at the Kaiser Permanente healthcare system in Orange County, California

  

 

(Anticipated Publication Date:  March 2010)

(Click above image for TV36 interview of Dr. Wascher)