History and Objectives: Considering the high incidence of breast cancer and its known prognosis and the existence of controversies on the role of patient’s age, tumor malignancy and its prognosis, this study was carried out on referrals of Mostafa Khomeini, Shohadayeh Tajrish and Loghman Hakim from 1993 to 1999.

Materials and Methods: The case-control strategy of this study was conducted on 200 patients with breast cancer. In this respect, 100 cases with lymphatic involvement and tumor size greater than 2.5 cm were selected as bed prognosis (Case group) and 100 cases were selected as good prognosis (Control). Then, their age was determined and tumor malignancy was determined using Bloom-Richardson criteria and they were selected as I, II and III groups. For statistical analysis, student’s t-test and X² test were applied and O.R. was determined for patients and population.

Results: This study was conducted on 200 patients in control (n=100) and case (n=100) groups. The age of control and case groups was 42.5±8.8 and 53.4±12.2 years respectively with a difference of 11 years between them (P<0.001). In addition, it was found out that breast cancer at ages greater than 50 years increases the risk of malignancy 17-fold. Meanwhile, malignancy type III relative to type I is more effective for the development of malignancy (5.6-fold) (P<0.0005).

Conclusion and Recommendations: It is concluded that age and malignancy play an essential role in the development of tumors with bad prognosis. It is recommended to apply preventive measures for known malignancies.