Dear Editor,

During our review of contemporary medical literature, we chanced upon an article authored by Qiu et al. [1], focusing on the link between thyroid cancer and major depression, schizophrenia, and bipolar disorder. We consider this topic highly significant, particularly given the large number of individuals affected by these disorders and the pressing need to comprehend their underlying pathophysiology.

According to the Global Cancer Statistics 2020, thyroid cancer ranked eleventh among all cancers, with 586,202 new cases and 43,646 deaths reported within the spectrum of 36 cancers in 2020 [2]. Thyroid cancer is divided into three primary histological categories: differentiated thyroid cancer, which includes papillary, follicular, and oncocytic thyroid carcinoma; medullary thyroid cancer, sometimes associated with multiple endocrine neoplasia type 2 syndromes; and anaplastic thyroid cancer, often arising from differentiated thyroid cancer and characterized by high mortality rates [3].

Major depression, schizophrenia, and bipolar disorder are highly impactful psychiatric conditions, each bearing substantial weight on individual well-being and societal health. Discussions surrounding genetic correlations among these disorders suggest that their current clinical boundaries may not adequately capture the interconnectedness of their underlying pathogenic processes, especially when examined from a genetic standpoint [4,5].

As the prevalence of psychiatric disorders and thyroid cancer continues to rise, a growing overlap between them has emerged, prompting us to further explore their relationship. In the study conducted by Qiu et al. [1], statistics from extensive genome-wide association studies to identify genetic variant loci linked to major depression, schizophrenia, bipolar disorder, and thyroid cancer were analyzed. A type of analysis called two-sample bidirectional MR was used to see if there is a link between major depressive disorder and thyroid cancer risk. Results, obtained by using two different methods, suggest that major depressive disorder might indeed increase the risk of thyroid cancer. The authors have also found a connection between genetic predisposition to schizophrenia and thyroid cancer. However, there was no evidence showing a causal relationship between bipolar disorder and thyroid cancer.

In conclusion, this study offers suggestive evidence indicating a positive association between major depressive disorder and schizophrenia with thyroid cancer, potentially carrying substantial clinical implications. Future studies are needed to clarify the biological mechanisms underlying these associations and to identify any potential confounding factors.