Tumors are diagnosed more often in the left breast than the right: It depends on where you are born

August 5, 2014, University of California, Irvine
Mammograms showing a normal breast (left) and a cancerous breast (right). Credit: Wikipedia.

Breast cancer is found more often in the left breast than in the right breast. The exact cause of this asymmetry is unknown. However, two researchers from the University of California, Irvine have found that this asymmetry is a function of where the patient was born. This surprising finding indicates that the environment in which a fetus develops can have profound influence decades later.

The two researchers, Trevor Sughrue and James Brody, analyzed the case files for over a million who were diagnosed in the United States over the past 40 years. Their results were published in the journal PLOS ONE.

They found that those born in Japan had more tumors in the left breast than in the right (114 in the left breast for every 100 in the right breast). While those born in Poland had more tumors in the right than the left breast (92 in the left breast for every 100 in the right).

However, no exists between Japanese-Americans born in the United States and the general population in the United States. This finding indicates the propensity for left breast tumors is not a genetic factor, but rather an environmental one. Women born in Japan are more likely to develop a tumor in their left breast than their right compared to women born in the United States.

The mechanism behind this finding is not known, but the finding highlights the growing recognition that the prenatal environment can effect the person's health decades later.

"This study not only illustrates the importance of the prenatal environment on the much later development of , but also highlights the power of analyzing . Small effects that are not usually noticed by looking at hundreds of patients come into focus. This technique should lead to a revolution in medicine." James Brody, Associate Professor of Biomedical Engineering at the University of California, Irvine said.

Explore further: Men develop breast cancer, too

More information: Breast Tumor Laterality in the United States Depends Upon the Country of Birth, but Not Race.  PLOS ONEDOI: 10.1371/journal.pone.0103313

Related Stories

Men develop breast cancer, too

July 8, 2014
(HealthDay)—While rare, breast cancer does occur in men and is often diagnosed at a later age and stage than in women, experts say.

Study finds risk of recurrence low in smallest HER2+ breast cancer tumors

June 2, 2014
Patients with specific HER2+ breast cancer tumors had a low risk of the cancer recurring five years after diagnosis, even without chemotherapy or treatment with a common antibody, according to a Kaiser Permanente study published ...

Breast cancer surgery rates vary greatly in Canada

June 18, 2014
(HealthDay)—Breast cancer surgery rates vary significantly across Canada, a new study finds.

Study identifies genes linked to breast cancer in East Asian women

July 23, 2014
A new study in East Asian women has identified three genetic changes linked to an increased risk of breast cancer. The research, led by Vanderbilt University investigators, was published online July 20 in Nature Genetics.

African-American women more likely to be diagnosed with higher risk breast cancer

June 9, 2014
A research study led by cancer specialists at MedStar Washington Hospital Center found that African-American women frequently present with biologically less favorable subtypes of breast cancer.

Molecular imaging finds novel way to knock down breast cancer

June 9, 2014
For years researchers have been developing molecular imaging techniques that visualize hormonally active breast cancer cells—specifically those testing positive for human epidermal growth factor receptor 2 (HER2). A recent ...

Recommended for you

Researchers develop a remote-controlled cancer immunotherapy system

January 15, 2018
A team of researchers has developed an ultrasound-based system that can non-invasively and remotely control genetic processes in live immune T cells so that they recognize and kill cancer cells.

Pancreatic tumors may require a one-two-three punch

January 15, 2018
One of the many difficult things about pancreatic cancer is that tumors are resistant to most treatments because of their unique density and cell composition. However, in a new Wilmot Cancer Institute study, scientists discovered ...

New immunotherapy approach boosts body's ability to destroy cancer cells

January 12, 2018
Few cancer treatments are generating more excitement these days than immunotherapy—drugs based on the principle that the immune system can be harnessed to detect and kill cancer cells, much in the same way that it goes ...

Cancer's gene-determined 'immune landscape' dictates progression of prostate tumors

January 12, 2018
The field of immunotherapy - the harnessing of patients' own immune systems to fend off cancer - is revolutionizing cancer treatment today. However, clinical trials often show marked improvements in only small subsets of ...

FDA approves first drug for tumors tied to breast cancer genes

January 12, 2018
(HealthDay)—The U.S. Food and Drug Administration on Friday approved the first drug aimed at treating metastatic breast cancers linked to the BRCA gene mutation.

Breast cancer gene does not boost risk of death: study

January 12, 2018
Young women with the BRCA gene mutation that prompted actress Angelina Jolie's pre-emptive and much-publicised double mastectomy are not more likely to die after a breast cancer diagnosis, scientists said Friday.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.