It’s a fact that thyroid cancer is more prevalent in women. One report counted the incidence of thyroid cancer in Xuhui District, Shanghai, over a 40-year period from 1973 to 2013. 2613 patients were counted in the study, of whom 671 were men and 1942 were women. The age of onset in men was 50.04 years, an average of 1.5 years later than in women (48.57 years).
The gender ratios of patients with each type of thyroid cancer are shown in Table 1.
| Table 1. Gender distribution of patients with each type of thyroid cancer | |
| Male to female ratio | |
| Papillary carcinoma | 1:2.83 |
| Follicular carcinoma | 1:4.1 |
| Medullary carcinoma | 0.75:1 |
| Undifferentiated carcinoma | 1:6 |
As seen, differentiated carcinomas, which account for more than 90% of all thyroid cancers (including papillary and follicular carcinomas), occur 3 to 4 times more frequently in women than in men.
What is the reason for this? There is no definitive explanation from the professional community.
In addition to common risk factors such as radiation and genetics, some studies have analyzed that female estrogen may be involved. The higher the level of estrogen in the body, the higher the incidence of thyroid cancer. 20 to 45 years old, estrogen levels are at a high level, and women in their 40s are the group with the highest incidence of thyroid cancer.
In addition, women’s increased stress at work and preference for foods high in iodine, such as seaweed, can lead to endocrine disruption and predispose to an active thyroid gland, and these factors may also be associated with an increased incidence of thyroid cancer in women.
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Co-written by Dr. Kai Guo, Cancer Hospital of Fudan University