Malignant neoplasms in people with hypothyroidism in Spain: A population-based analysis.

Hypothyroidism was associated with a significantly increased overall risk of cancer in the Spanish population.

• Study used the population-based database BDCAP (Base de Datos Clínicos de Atención Primaria) with a total of 2,414,165 patients diagnosed with hypothyroidism in 2019.
• The overall relative risk (OR) of cancer in hypothyroid patients compared to non-hypothyroid population was 1.73 (95% CI: 1.72-1.74; P<0.0001).
• Cross-sectional study design was used to analyze relative risk of cancer.

Increased cancer risk associated with hypothyroidism was observed in both men and women, with men showing a higher risk.

• Men with hypothyroidism had an OR of 2.15 (95% CI: 2.13-2.17; P<0.0001).
• Women with hypothyroidism had an OR of 1.67 (95% CI: 1.636-1.68; P<0.0001).
• The cancer risk elevation was statistically significant in both sexes.

Hypothyroid persons aged 65 years or older had a reduced risk of cancer compared to non-hypothyroid individuals.

• Hypothyroid patients aged 65 or over showed an OR of 0.98 (95% CI: 0.97-0.98; P<0.0001) for overall cancer risk.
• This represents a statistically significant decreased risk compared to the non-hypothyroid population.
• This finding contrasts with the elevated cancer risk seen in younger hypothyroid patients.

Hypothyroid patients aged 65 or over showed a decreased risk of specific site cancers.

• Decreased cancer risk in older hypothyroid patients was observed for cancers of the bladder, colorectal, gastric, pancreatic, and prostate.
• These site-specific reductions were identified specifically in the 65 years or older age group.
• This age-dependent inverse association with multiple cancer sites was a notable finding of the study.

Hypothyroid patients receiving replacement therapy exhibited higher cancer risk compared with patients without treatment.

• Hypothyroid patients on replacement therapy had an OR of 1.30 (95% CI: 1.28-1.31; P<0.0001) for cancer compared to untreated hypothyroid patients.
• This finding suggests that treatment status modifies the cancer risk association in hypothyroid patients.
• The nature of the replacement therapy was not further specified in the abstract.

Socioeconomic characteristics had limited influence on the association between hypothyroidism and cancer.

• Factors analyzed included income level, municipality size, country of birth, and employment situation.
• Despite examining multiple socioeconomic variables, none substantially modified the hypothyroidism-cancer association.
• The study used a population-based primary care database allowing for analysis of these socioeconomic characteristics.