We aimed to assess relative survival (RS) and determinants of excess mortality rate in patients with head and neck squamous cell carcinomas (HNSCC) and thyroid cancer in Golestan province, Northern Iran.
We recruited new primary HNSCC and thyroid cancer cases from Golestan, 2006–2016. Five-year age-standardized RS with their 95% confidence intervals (CIs) were calculated. The relationships between different variables with excess mortality rates were assessed by estimating adjusted excess hazard ratios (aEHRs) with their 95% CIs.
Overall, 718 cases of HNSCC and 386 thyroid cancer cases were enrolled. Five-year age-standardized RS (95% CI) were 36% (31−41) and 61% (52−69) in HNSCC and thyroid cancer patients, respectively. There were significant relationship between excess mortality rates in HNSCC patients with metastasis (aEHR= 3.31; 95%CI: 2.26–4.84), treatment type (4.19; 2.54–6.91, for no treatment as compared to receiving both surgery and chemoradiotherapy), age (2.16; 1.57–2.96, for older age group) and smoking (2.00; 1.45–2.75, for smokers as compared to non-smokers). Determinant of the excess mortality in thyroid cancer patients included metastasis (19.65; 8.08–47.79), tumor morphology (12.27; 4.62–32.58, for anaplastic cancer as compared to papillary cancer), treatment type (8.95, 4.13–19.4, for no treatment as compared to receiving both surgery and iodine therapy) and age (2.31; 1.17–4.54, for older age group).
Our findings suggested low RS for thyroid cancer in our population, while the estimates for HNSCC were comparable with other population. Metastasis, treatment type and age were determinants of mortality both in thyroid and HNSCC patients.
- • We assessed survival rates for head and neck (H&N) and thyroid cancer cases in Iran.
- • Five-year relative survival (RS) and excess hazard ratios (EHR) were calculated.
- • Five-year age standardized RS were 36% in H&N and 61% in thyroid cancer patients.
- • Metastasis, treatment type and age are related to EHR in H&N and thyroid cancers.
- • Low survival rates warrants further studies on healthcare access in thyroid cancer.
Cancers of the oral cavity, sinonasal cavity, pharynx, and larynx are mostly squamous cell carcinomas raised from their mucosal surfaces, so called as head and neck squamous cell carcinomas (HNSCC) . Although thyroid cancer is not classified as HNSCC, it is often grouped with these cancers, as head and neck cancers (HNC), because of its anatomical location . HNSCC were the seventh most common cancer worldwide in 2020. Thyroid cancer is the most common endocrine related malignancy and ninth most common cancer type based on data from International Agency for Research on Cancer (IARC) . According to the IARC Global cancer statistics for year 2020, 93,1931 new cases of HNSCC were estimated to occur in the world, with and age standardized incidence rate (ASR) of 10.1 per 100,000 person-year., and the ASR of this cancer in Iran was 5.2 per 100,000 person-year (4413 new cases). The thyroid cancer incidence rate worldwide was 6.6 per 100,000 person-year (586 202 new cases), and the estimated number of new cases of thyroid cancer in Iranian population was 4114 with the ASR of 4.4 per 100,000 person-year .
Cancer survival is a crucial information for cancer control planning, and it can serve as indicator of the efficacy of existing strategies for the efficient management of the cancer. Cancer survival information can provide health officials and policymakers on areas of care that may need improvement to better serve cancer patients . Net survival (NS), the probability of survival when the cancer under study is the only possible cause of death. Net survival is useful in practice for comparing cancer survival between different populations and on the same population over time, because it does not depend of mortality due to causes other than cancer, which varies over time and between countries . Population-based cancer registries typically consider relative survival (RS) to estimate NS . RS is defined as the ratio of the observed to the expected survival (all-cause survival that would be expected in the absence of the specific disease under study) .