By David Liu, PHD

Sunday March 4, 2012 (foodconsumer.org) -- Women receiving radiation therapy (ionizing radiation or x-ray in this case) for Hodgkin lymphoma can increase risk of developing breast cancer years later, according to new research.

Medical radiation as a carcinogen is known to be harmful and can increase cancer risk.  But it has been unknown until now how much risk for breast cancer the radiation-based therapy indicated to treat Hodgkin lymphoma can increase.

Recently on Medscape, Maurie Markman, MD cited studies as saying that women who received chest wall radiation for Hodgkin lymphoma were at 25 percent increased risk for secondary breast cancer during a decade-long follow-up, compared to those who did not receive the treatment.  The risk could be higher if the patients were followed up for a longer period.

Ionizing radiation or x-ray can be particularly harmful to women with a genetic variant of the FGFR2 gene.  Researchers found that among women who had the variant, those who  received radiation therapy and chemotherapy were 59 percent more likely to develop breast cancer, compared to those who received chemotherapy alone.

Researchers examined the possible effect of 14 individual single nucleotide polymorphisms (SNPs) that were previously known to influence risk of breast cancer or second breast cancer induced by radiation therapy intended to treat Hodgkin lymphoma.

They found one particular SNP, rs12119648, which is related to FGFR2 gene, highly significantly associated with risk for a secondary breast cancer induced by radiation therapy for Hodgkin lymphoma.  The increase in the risk was 59 percent.

The findings suggest that women who are diagnosed with Hodgkin lymphoma should be aware of this elevated risk for secondary breast cancer associated with radiation therapy intended to treat the disease.  And the best treatment should be chemotherapy without chest wall radiation.

No matter a women carries the genetic variant or not, ionizing radiation used for medical diagnosis and treatment is alway a carcinogen recognized by the U.S. National Toxicology Program.  That means that using such a diagnstic tool or treatment can increase a person's cancer risk, meaning that some people will have develop cancer after exposure to radiation (x-ray).  There is no safe dose for x-ray.  The more x-ray you are exposed to, the higher risk you have to face.

Dr. John Gofman, late nuclear physician and scientist, said 75 percent of breast cancer cases had somethng to do with x-ray or ionizing radiation used for medical diagnosis and treatment.