BACKGROUND: The incidence of thyroid cancer has rapidly increased and ecological evidence suggests this is due in some part, to over-diagnosis. Understanding pathways to diagnosis could help determine whether unnecessary diagnosis can be avoided. METHODS: We recruited a population-based sample (n=1007) of thyroid cancer patients diagnosed between July 2013 and August 2016 from Queensland, Australia (response rate 67%). We used information from structured telephone interviews to describe diagnostic pathways for thyroid cancer, to investigate factors associated with diagnostic pathways, and to assess the most prevalent modes of diagnoses by which the lowest-risk, potentially over-diagnosed thyroid cancers (intra-thyroidal micro-carcinomas) are detected. RESULTS: Only 38% of participants presented with symptoms potentially related to thyroid cancer. Older age at diagnosis was associated with a lower prevalence of symptomatic diagnosis (prevalence ratio [PR]: 0.46; 95% confidence interval [CI] 0.31-0.68, for 70-79 vs <30 years) as was frequent medical contact, while living in rural/regional areas was associated with a higher prevalence of symptomatic diagnosis (PR: 1.17; 95% CI 1.00-1.37, rural/regional areas vs major cities). Symptomatic diagnosis also occurred more for those whose tumors had adverse histopathological features (larger size, lymph node involvement, lymphovascular invasion). The likelihood of diagnosis of intra-thyroidal micro-carcinomas was greatest for those having surgical resection or monitoring for benign thyroid disease (PR: 3.87; 95% CI 2.81-5.32 and PR: 2.21; 95% CI 1.53-3.18 respectively). CONCLUSIONS: A minority of newly detected thyroid cancer cases were diagnosed because of symptoms. Access to medical care and factors related to cancer aggressiveness were associated with how diagnoses occurred. The likelihood of diagnosing the lowest-risk thyroid cancers was higher in situations related to management of other thyroid conditions. Adherence to thyroid management guidelines could reduce some thyroid cancer over-diagnosis, but ultimately we need better diagnostic tools to differentiate between indolent cancers and those of clinical significance.
|Authors||Rahman, Sabbir; McLeod, Donald S A; Pandeya, Nirmala; Neale, Rachel E; Bain, Chris; Baade, Peter D; Youl, Philippa; Jordan, Susan J|
|Grant ID||NHMRC APP1047733|
|Funding Body||National Health and Medical Research Council of Australia|