One of the most common cancers in women, which is the second leading cause of death among women in the United States, is breast cancer 1, 2, 3. Tumor and lymph node resection is a common treatment for breast cancer patients in the form of radiation therapy, hormone therapy or chemotherapy, and often carries many risks for patients with large tumors 4, 5. Most breast cancer patients are treated and survive with these treatments. Gene expression tests can be effective in diagnosing and treating breast cancer 6, 7, 8. Programmed cell death protein is a protein from the family of immunoglobulins that has receptors PDL1 and PDL2 and is known as an inhibitory protein. PD1 is expressed on the surface of T cells and B lymphocytes and normal killer cells 9, 10, 11. Although many studies have shown a link between gene expression and disease pathogenesis, little is known about the expression of PD1 gene and breast cancer 12, 13. Recent studies have shown that PD-1 gene expression is associated with BC pathogenesis, but studies indicate the importance of PD-1 gene in regulating T cell activity 14. In this study, we investigated the expression of PD1 gene in women with breast cancer in comparison with healthy individuals in Sistan and Baluchestan province, Zahedan.

A total of 50 patients were recruited in this study, 25 BC patients and 25 healthy controls. The mean age of BC patients and the healthy controls were 2.75 ± 12.18 and 30.6 ± 2.6 respectively. No significant difference was observed in age distribution between the BC patients and control group.

After cancers such as lung, stomach and liver cancers, breast cancer is one of the most common cancers in the female population of the world, which can be the most common cause of death in women. programmed cell death is called apoptosis, which is clinically important because failure to control and regulate the mechanism of apoptosis leads to overexpression of certain genes and pathogenesis and plays an important role in the development of many cancers 15. PD1 protein is a member of the CD28 family of immunoglobulins and has two receptors, PDL1 and PDL2. This protein has an inhibitory role. Inhibitory function and inhibitory signals of PD1 protein through its receptors lead to activation of T cell function, tolerance, and tissue damage due to immunity 16. There have also been many studies on PD1 gene polymorphisms and their role in breast cancer patients compared to healthy individuals, which have been introduced as prognosticators in the diagnosis and treatment of various cancers, including breast cancer. In addition, gene mutations have played a significant role in the development of breast cancer. Many studies have been conducted in this field. Eight studies (Chang, 2007,55 Cobliegh, 2005,47 Esteva, 2005,48 Gianni, 2005,49 Cronin, 2004,44 Habel, 2006,50 Mina, 2006,51 and Paik, 200428) have examined the expression of different genes in breast cancer compared to healthy individuals using different methods such as real-time PCR or immunohistochemistry 17, 18, 19, 20, 21, 22, 23, 24. Cronin and colleagues showed that there is a significant relationship between PDL1 gene expression and the progression of breast cancer. The group and their colleagues studied the expression of five genes in breast cancer. In a clinical study, Oratz R and colleagues also investigated gene expression variation and their association with a variety of cancers, including breast cancer 25. They showed that in patients with breast cancer, the expression of PD1 was significantly increased. According to these studies, the expression of PD1 gene can play an effective role in the development and progression of breast cancer. Zhou and colleagues also showed a link between PD1 gene expression and the incidence of breast cancer 26. They showed that the expression level of PD1 was higher in patients with breast cancer than in the control group. Therefore, gene expression can serve as a prognostic marker in screening and immunotherapy in patients with breast cancer.

The results of our study showed that the expression level of PD1 gene in patients with breast cancer was significantly higher compared to healthy individuals and it can be concluded that the expression of PD1 gene can be a prognostic factor in the early diagnosis of breast cancer. Therefore, it is suggested that more studies be performed on the relationship between the expression of more genes and breast cancer. In addition, according to the findings of the study have been obtained only from the people of Sistan-Baluchistan province, fertility studies in different ethnic groups are required.