Introduction: Acute Toxoplasmosis is more critical in immunocompromised patients with cancer. The present study was conducted to investigate the anti-Toxoplasma gondi antibodies and assess the toxoplasmosis risk in women with breast masses in western of Iran in 2012. This research was done as a case-control study on women who referred to the treatment centers in cities of Kermanshah and Ilam in 2011.

Materials and methods: 60 women with breast cancer were selected as cases, and also 60 healthy ones as the control group. They were evaluated in terms of IgG, IgM, estrogen and progesterone levels using immunoassay method. Women in this study were in the secretory phase and were under the age of menopause. Results were analyzed using SPSS software 16 with independent T test.

Results: Relationship between Toxoplasma gondii (T. gondii) infection and breast cancer was statistically significant (P<0.01). There was a significant relationship between anti-Toxoplasma IgG antibody and breast cancer (P=0.01). Women with breast cancer and healthy women were not reported positive in terms of IgM anti-Toxoplasma. Significant relationship was detected between estrogen and Toxoplasma in women with breast cancer (P<0.01). There was no significant relationship between the level of progesterone and anti-Toxoplasma antibodies. A total of 30 patients (50%) from the women under study had the tumor marker CEA 19-9 (Carcino embryonic antigen).

Conclusion: Patients with breast tumors may be at risk of opportunistic infections such as toxoplasmosis. Therefore, periodic examination of breast cancer patients should be conducted by clinicians to prevent the potential occurrence of toxoplasmosis.