Risk of developing breast cancer among female Hodgkin lymphoma patients

This study looked at the risk of developing breast cancer while on hormone replacement therapy for female patients who were treated with radiation for Hodgkin lymphoma. The authors concluded that radiation therapy significantly increased the risk of developing breast cancer, and hormone replacement therapy did not significantly increase the risk of developing breast cancer. 

Patients with Hodgkin lymphoma (HL) are often treated with radiation therapy (RT). Chest RT can increase the risk of developing breast cancer in patients with HL. It is unclear if other risk factors may increase the risk of developing breast cancer in HL patients.

Because of treatment, some female HL patients may go into menopause early. In order to deal with the symptoms of menopause, some patients will take hormone replacement therapy (HRT). Some hormones can cause breast cancer to grow. More research is needed to determine if HRT increases the risk of developing breast cancer in female HL patients. 

This was a case-control study. 174 HL patients with breast cancer were selected as cases. 466 HL patients without breast cancer were selected as controls (comparison). The controls were picked to be similar to the cases so only the effects of RT and HRT could be studied.

99% of cases were treated with RT. 90% of controls were treated with RT. Patients who received an average of 36 Gy of radiation were 4.7 times more likely to develop breast cancer compared to patients who received very little or no radiation.

20.1% of cases received HRT. 27.2% of controls received HRT. HRT did not significantly increase the risk of developing breast cancer among female HL patients.

Women who used oral birth control for 15 years or more were 2.55 times more likely to develop breast cancer compared to women who never used oral birth control. 

The study concluded that hormone replacement therapy does not significantly increase the risk of developing breast cancer, but chest radiation therapy significantly increases the risk of developing breast cancer in patients treated for Hodgkin lymphoma.