'Pressing need' for quality data on treatment options for low-risk thyroid cancers
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Models projecting incidence of low-risk papillary thyroid cancers suggest there will be more than 200,000 new thyroid cancer diagnoses during the next 5 years, with at least 67,000 of those cases qualifying as candidates for active surveillance due to small tumor size, according to findings published in JAMA Otolaryngology Head & Neck Surgery.
“In 2015, the American Thyroid Association guidelines for the first time endorsed active surveillance as an alternative to immediate surgery in select patients with low-risk papillary thyroid cancer (PTC),” Benjamin R. Roman, MD, MSHP, a head and neck cancer surgeon and cancer health services researcher at Memorial Sloan Kettering Cancer Center, New York, and colleagues wrote in the study background. “To date, very few patients in the U.S. are being treated with active surveillance. The numbers of newly diagnosed patients with PTC who may be active surveillance candidates in the coming years are not known.”
Modeling trends
Using the Surveillance, Epidemiology, and End Results (SEER) database from the National Cancer Institute, Roman and colleagues analyzed age-adjusted incidence and raw numbers of PTC between 2004 and 2016, and then converted age-adjusted incidence rates to U.S. population numbers using 2010 Census Bureau statistics. Researchers defined a group of patients with low-risk PTC as those with papillary histology staged clinically T1, clinically node-negative neck, no distant metastases, and subgroups of patients with tumors 1.5 cm or smaller, and those with tumors 1 cm or smaller.
The researchers used joinpoint regression analysis statistical software to predict PTC rates beyond 2016, identifying the most recent inflection points in the annual percent change in the incidence of PTC. Available 2016 data showed a possible beginning of a plateau in PTC rates; researchers modeled two future predicted rates with one and two inflection points to describe a range of possibilities and raw numbers for future trends.
“The first annual percent change model with one inflection point (annual percent change, 1.41%) reflects a maximum number of patients expected to be diagnosed and treated for PTC starting in 2017; this is based on the overall rising incidence in the several years prior,” the researchers wrote. “The second annual percent change model with two inflection points (annual percent change, 2.09%) describes the possible leveling off of increased incidence seen from 2014 to 2016, and therefore suggests there may be lower numbers and expected trends.”
From 2004 to 2016, 87% of patients with thyroid cancer had histologically confirmed PTC, 50% of which were low risk. Among patients with T1 tumors, 84.5% had tumors of 1.5 cm or smaller, and 63.5% had tumors of 1 cm or smaller.
The researchers found that the estimated total number of patients with T1 tumors in the next 5 years (2020-2024) will be 92,635 to 113,395. Using a size cutoff of 1.5 cm or smaller and 14% exclusion of cases inappropriate for active surveillance, the estimated total number of patients eligible for active surveillance during the next 5 years will be 67,344 to 82,405.
Using a further size cutoff of less than 1 cm and 14% exclusion of inappropriate for active surveillance, the estimated total number of patients eligible for active surveillance during the next 5 years will be 50,578 to 61,925, according to researchers.
Guidelines, support systems needed
“Our projections suggest that there will be 212,215 to 259,785 new thyroid cancer diagnoses with at least 67,344 patients having tumors of 1.5 cm or smaller, and at least 50,578 having tumors smaller than 1 cm over the next 5 years who will be potential candidates for active surveillance as a treatment strategy,” the researchers wrote. “Thus, there will be a pressing need for further development of high-quality data on treatment options (including active surveillance and local ablative therapies), guidelines and support systems at the organizational and patient level geared specifically for this challenge.” – by Regina Schaffer
Disclosures: The authors report no relevant financial disclosures.
Perspective
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Angela M. Leung, MD, MSc
Active surveillance of biopsy-proven, low-risk thyroid cancers measuring up to 1 cm has been done in Japan for nearly two decades. Long-term monitoring shows that there is relatively low risk for this type of non-operative management of malignant thyroid nodules among appropriately selected patients. The U.S. has only more recently similarly adopted smaller active surveillance single-institution trials of low-risk thyroid cancers, including of some tumors measuring up to 1.5 cm. The results of the present study show that, based on the estimated prevalence of low-risk thyroid cancers in the U.S. population, there may be over 82,000 patients with thyroid tumors (up to 1.5 cm) who might be able to be monitored in this way over the next 5 years. As non-operative monitoring of biopsy-proven low-risk thyroid cancers has been not done in the U.S. on the large population level, the appropriate structure of programs, resources, and support systems would have to be in place before this can be done.
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