Researchers conducted the first population-based study of an unselected MTC cohort compared with the general population.
Survival rates of patients with hereditary medullary thyroid carcinoma (MTC) diagnosed by screening, patients without regional metastases, and those with stage I, II, or III disease are comparable to those of the general population. However, individuals with distant metastases have worse disease-specific survival (DFS), according to a study published in Thyroid.
Jes Sloth Mathiesen, MD, of Odense University Hospital and the University of Southern Denmark, Odense, Denmark, and colleagues conducted the first population-based study of an unselected nationwide MTC cohort. The researchers aimed to identify subgroups with survival similar to that of the general population and to investigate prognostic factors for long-term biochemical cure and DFS.
The researchers evaluated 220 patients from the nationwide Danish MTC cohort who were treated between 1997 and 2014. They found that overall survival (OS) rates were similar between the general population and patients diagnosed with hereditary MTC by screening (hazard ratio [HR], 1.5), patients without regional metastases (HR, 1.4), and patients with stage I disease (HR, 1.3). The OS rates were similar for those with stage II disease (HR, 1.1) and stage III disease (HR, 1.3).
A multivariate analysis found that the presence of distant metastases (HR, 12.3) predicted worse DFS. In addition, the absence of regional lymph node metastases (OR, 40.1) was the only independent prognostic factor for long-term biochemical cure.
The median follow-up time was 6.8 years, and as of the latest follow-up, 76 patients had died (51 from MTC and 25 from other causes). The investigators compared the MTC patients with a reference population that included 11,000 controls (6,550 females and 4,450 males).
Endocrinologist Bryan McIver, MD, who is deputy physician-in-chief at Moffitt Cancer Center, Tampa, Florida, said this study is important because it provides reliable evidence that the current standard of care is truly effective in the majority of cases if MTC is diagnosed at an early stage.
According to McIver, MTC was first described as a unique form of thyroid cancer in 1958, but it is difficult to study because it is a rare subtype of thyroid cancer. Therefore, very few clinical trials investigate new treatments for early-stage MTC. “Our treatment approaches, usually surgery and sometimes radiation therapy in more extensive disease, are based on retrospective studies performed in a few large academic medical centers,” McIver told Cancer Network.
McIver noted that this study was conducted in Denmark, where there is universal healthcare, and so that must be considered. However, he said, the findings support the notion that researchers are developing the right type of studies for the right type of patients.
“This study confirms that patients with Stage 4A, 4B, and 4C MTC are rarely cured, and we therefore need to continue to develop prospective clinical trials of new treatments for these patients. Those clinical trials might include new surgical techniques, more extensive use of radiation therapy, both externally and internally administered, and drug-based treatments,” said McIver.