In a recent study published within the journal Scientific Reports, researchers used a nationwide case-control study of Taiwanese residents to research the association between human papillomavirus (HPV) and thyroid cancer. Analyses of the three,062 thyroid cancer patients and 9,186 healthy controls revealed that individuals with a previous HPV infection had greater than double the likelihood of developing thyroid cancer than those without the infection (odds ratios 2.199 for HPV patients). This research presents the primary concrete evidence of a carcinogen for thyroid cancer, probably the most common endocrine cancer and a growing concern worldwide.

Study: Association of thyroid cancer with human papillomavirus infections. Image Credit: Naeblys / Shutterstock

What will we find out about thyroid cancer?

Thyroid cancer refers back to the growth and development of malignant (cancerous) cells within the thyroid gland, a butterfly-shaped gland at the bottom of the neck. Despite being probably the most common endocrine cancer on the planet today, thyroid cancer and particularly its causative agents remain poorly understood. Alarmingly, the prevalence of this potentially lethal disease has been rising rapidly. In the USA of America (US) alone, thyroid cancer incidence rates have greater than tripled over the past three a long time, with current reports revealing that 45,000 latest cancer cases are discovered inside the country annually.

The thyroid gland is a vital endocrine organ whose secretions govern normal respiratory, heart rate, body temperature (homeostasis), and nervous system function. Malignancies of this gland, though treatable, may lead to severe disruptions in these bodily functions, leaving survivors with life-long comorbidities. Despite intensive recent research geared toward unraveling the underlying causes of thyroid cancers, a definitive carcinogen stays elusive. The present clinical and scientific consensus is that thyroid cancers arise resulting from a mixture of genetic, environmental, and behavioral aspects.

Human papillomavirus (HPV) is a sexually transmitted virus and probably the most common sexually transmitted infection (STI) globally. Despite the existence of various vaccines against HPV, 43 million people were estimated to be infected by the virus in 2018 alone. While severe HPV infections lead to the event of warts and scarring across the mouth and genital areas, the virus’ actual danger lies in its carcinogenicity – HPV (including asymptomatic infections) has been identified as the foundation explanation for quite a few cancers and is estimated to be accountable for 3% of female, and a couple of% of male cancers worldwide.

Recent research has identified HPV particles in thyroid nodules (each benign and malignant), however the association between the virus and thyroid cancer stays unexplored.

“Because the role of human papillomavirus in the event of thyroid cancer presents an intriguing possibility, this study goals to research the association of human papillomavirus infection with the event of thyroid cancer using a nationwide population-based study.”

In regards to the study

Data for the current study was collected from Taiwan’s Longitudinal Health Insurance Database (2005) and consisted of ambulatory care claims, prescriptions, medical facility reports, and inpatient claims mandated by the Taiwanese government. Thyroid cancer and HPV infections were defined and recorded as per the International Classification of Diseases, Ninth Edition, Clinical Modification (ICD-9-CM) guidelines.

This case-control study included thyroid cancer patients above the age of 20 and healthy controls in a 1:3 ratio. Following cross-referencing thyroid cancer cases listed within the Insurance Database against the Taiwan Cancer Registry, 3,062 patients were identified as eligible for inclusion in analyses. Propensity rating matching was used to discover 9,186 medically insured individuals with no history of thyroid cancer.

“Propensity rating matching is a quasi-experimental method that permits us to construct a man-made control group by matching each patient with thyroid cancer with a non-thyroid cancer beneficiary of comparable characteristics.”

HPV infections were confirmed using positive polymerase chain response (PCR) tests. Statistical analyses comprised t-tests and chi-square tests to elucidate the differences in cases and controls based on medical and demographic data. Multivariate logistic regressions, corrected for participant anthropometrics and demographics (age, sex, geographic location, income, medical history, and urbanization level), were used to estimate the associations between HPV and thyroid cancer quantitatively. Odds ratios (ORs) were computed to quantify the chance of developing thyroid cancer following HPV infection.

Study conclusions

The current study found that patients infected with HPV were 2.199 times more prone to subsequently develop thyroid cancer in comparison with those with no history of the virus. This means a powerful association between the 2 diseases and presents the primary evidence of HPV as a thyroid cancer-inducing carcinogen. Propensity rating matching and statistical analyses confirmed that no statistically significant differences between cases and controls exist, strengthening support for HPV because the driving force behind observed thyroid cancer incidence.

Despite the study being restricted to Taiwan, thereby limiting the generalization of those findings, this study may shine a lightweight on the hitherto unexplained rise in thyroid cancer cases globally. Multivariate analyses revealed that computed ORs remain stable regardless of age or sex, albeit these ORs are lower for thyroid cancers in comparison with other HPV-induced cancers.

“If further research confirms the link between human papillomavirus and thyroid cancer, human papillomavirus vaccinations could possibly be used as a safety measure. While further research is required to corroborate this association and understand the underlying mechanisms, our study emphasizes the potential role of human papillomavirus in the event of thyroid cancer and the clinical implications thereof. This study supports the need for clinicians, researchers, and public health practitioners to concentrate on the possible connection between human papillomavirus and thyroid cancer.”