Alopecia Areata and the Risk of Thyroid Cancer
It’s well known that patients with alopecia areata are at increased risk for thyroid abnormalities. In fact, autoimmune thyroid disease is among the most common comorbidities seen with alopecia areata. One association which seems real - but quite unexpected - is the increased risk of thyroid cancer that patients with alopecia areata might have.
In 2018, Lee et al performed a study to better understand the cancer risks in patients with alopecia areata. The authors studied 668,604 patients who were treated for alopecia from 2007 to 2014 and compared data to age- and sex-matched control subjects. Compared to controls, AA patients had a 4 % increase in overall cancer risks (hazard ratio (HR), 1.043; 95% confidence interval (CI), 1.022-1.065 and patients with AT/AU had a 7% increased risk ( HR, 1.07; 95% CI, 1.013-1.129, respectively).
The authors found that the risks of cancers of the oral cavity, esophagus, liver, biliary tract, pancreas, larynx, lung, kidney, breast, cervix, ovary, uterus, testis, nerve, skin cancers; and lymphoma, multiple myeloma, and leukemia, were not increased in alopecia patients. An increased risk of thyroid cancer was identified in patient with AA or AT/AU. In AA patients alone, the risks of bladder and prostate cancers were increased.
Other studies linking thyroid cancer and alopecia areata
A 2019 meta-analysis by Lee and colleagues sought to determine the health conditions that are increased or decreased in patients with alopecia areata. The authors evaluated 87 published studies. Regarding cancer risk in patients with alopecia areata, they identified a nearly two fold increased risk of thyroid cancer. There was no increased risk for lung, breast, bladder, lymphoma and leukemia. The authors identified decreased risk of gastric, colon and liver cancer.
In 2021, Lugović-Mihić described a patient with AA of the beard and thyroid cancer.
Final Comment
There is enough data accumulating now to convincingly show that patients with alopecia have a higher risk of cancer. The magnitude of risk overall is fairly small. The risks appear small enough that screening guidelines have not been introduced. Everyone with alopecia areata requires a TSH. However, it’s important to be aware that TSH levels are usually normal in patients with thyroid cancer. Patients with a lump in the neck, difficulty swallowing, a pain in the neck, swelling in the neck, a feeling that shirt collars are too tight, a change in the voice (to a hoarse voice) or patients with enlarged lymph nodes in the neck require further evaluation for possible thyroid cancer.
The findings of these studies are important. Patients with alopecia totalis and universalis are probably at even greater risk than patients with less severe forms (like patchy AA). This is backed up by a 2023 study by George et al.
There is something special about thyroid cancer. It stands out as a type of cancer that is clearly increased in patients with AA. It may not be the only cancer that is increased as patients with alopecia totalis and universalis have a higher rate of non-melanoma skin cancer, melanoma skin cancer, and lymphoma compared to patients with milder forms and compared to the general population.
REFERENCES
Lee JH et al. Cancer risk by the subtype of alopecia. Sci Rep . 2018 Jun 27;8(1):9748. doi: 10.1038/s41598-018-28142-1.
Lee S et al. Comorbidities in alopecia areata: A systematic review and meta-analysis. J Am Acad Dermatol. 2019 Feb;80(2):466-477.e16.
Lugović-Mihić L et al. CAN SKIN BE A MARKER FOR INTERNAL MALIGNANCY? EVIDENCE FROM CLINICAL CASES. Acta Clin Croat . 2021 Dec;60(4):711-721. doi: 10.20471/acc.2021.60.04.19.
George P et al. Incidence Rates of Infections, Malignancies, Thromboembolism, and Cardiovascular Events in an Alopecia Areata Cohort from a US Claims Database., Dermatol Ther (Heidelb). 2023 Aug; 13(8): 1733–1746.