The impact of age and gender on papillary thyroid cancer survival

Abstract

Context: Thyroid cancer predominately affects women, carries a worse prognosis in older age, and may have higher mortality in men. Superimposed on these observations is the fact that most women have attained menopause by age 55 yr.

Objective: The objective of the study was to determine whether men contribute disproportionately to papillary thyroid cancer (PTC) mortality or whether menopause affects PTC prognosis.

Design: Gender-specific mortality was normalized using age-matched subjects from the U.S. population. Multivariate Cox proportional hazard regression models incorporating gender, age, and National Thyroid Cancer Treatment Cooperative Study Group stage were used to model disease-specific survival (DSS).

Participants and setting: Patients were followed in a prospective registry.

Main outcome measure: The relationships between gender, age, and PTC outcomes were analyzed.

Results: The unadjusted hazard ratio (HR) for DSS for women was 0.40 [confidence interval (CI) 0.24-0.65]. This female advantage diminished when DSS was adjusted for age at diagnosis and stage with a HR encompassing unity (HR 0.72, CI 0.44-1.19). Additional multivariate models of DSS considering gender, disease stage, and various age groupings showed that the DSS for women diagnosed at under 55 yr was improved over men (HR 0.33, CI 0.13-0.81). However, the HR for DSS increased to become similar to men for women diagnosed at 55-69 yr (HR 1.01, CI 0.42-2.37) and at 70 yr or greater (HR 1.17, CI 0.48-2.85).

Conclusions: Although the overall outcome of women with PTC is similar to men, subgroup analysis showed that this composite outcome is composed of two periods with different outcomes. The first period is a period with better outcomes for women than men when the diagnosis occurs at younger than 55 yr; the second is a period with similar outcomes for both women and men diagnosed at ages greater than 55 yr. These data raise the question of whether an older age cutoff would improve current staging systems. We hypothesize that older age modifies the effect of gender on outcomes due to menopause-associated hormonal alterations.

Fig. 1.

A, Distribution of NTCTCSG registry patients by age and disease stage at diagnosis. NTCTCSG stage was not available for three men and one woman. P < 0.001 for gender differences in distribution of age groups and stages (Kruskal-Wallis test). B, Number (shown on left) and percentage (shown on right) of deaths and thyroid cancer deaths in NTCTCSG registry patients. Total number of patients was 3572, number of females was 2619, and number of males was 953.

Fig. 2.

A, Overall survival of United States population compared with overall survival of thyroid cancer registry patients, with survival displayed separately for males (left panel) and females (right panel). B, Overall survival of United States population compared with disease-specific survival of thyroid cancer registry patients, with survival displayed separately for males (left panel) and females (right panel). C, Disease-specific survival of thyroid cancer registry patients by gender (left panel) and overall survival of United States population by gender (right panel). [Source for U.S. population is United States life tables, 2003 (23).]

Fig. 3.

HR (shown as black squares) and 95% CI for HR (shown as top and bottom of rectangle) for DSS for females compared with males. *, P value for gender difference = 0.016.