American Thyroid Association 86th Annual Meeting:
Restraint Needed in Treating Thyroid Microcarcinomas
Attitudes are changing about how to treat the most common endocrine malignancy--papillary thyroid cancer (PTC), according to Ian D. Hay, MD, PhD, the Dr. Richard F. Emslander Professor of Endocrinology and Nutrition Research at the Mayo Clinic in Rochester, Minnesota, on September 21 at the American Thyroid Association's (ATA) annual meeting1, in Denver, Colorado.
"The pendulum is swinging," said Dr. Hay, as he began his presentation, "Changing Attitudes to the Most Common Endocrine Malignancy, T1 PTC. "Much of the so-called ''epidemic'' in thyroid cancer over the past several years is due to the increased detection of these smaller, and smaller, tumors coupled with the traditional thinking to treat any and all cancers.”
More recently, consideration has begun to shift on the management of these smaller tumors, which make up 80% of thyroid cancers globally, suggested Dr. Hay. “Growing numbers of experts are suggesting much less invasive treatment, or no treatment at all, an approach now called--active surveillance with curative intent, or ASCI,” Dr. Hay said.
Overdiagnosis Reaching Peak
More frequent detection of these tumors, due to advanced screening methods, is behind the so-called ''epidemic'' in thyroid cancer, said Dr. Hay. In the U.S., 63,000 new cases of thyroid cancers were expected in 2014, compared to 37,200 in 2009.2
Yet, “left alone, or treated minimally, many of these tumors pose no problems,” said Dr. Hay, who cited evidence from his own Mayo Clinic data, which replicated other research. "At Mayo, we have also seen, a tripling of the numbers of patients diagnosed with T1 PTC, since 1994," he said. “During 8 decades of record keeping, the proportion of microcancers has doubled from 15 to 34%.”
Concerns about overdiagnosis surfaced as early as a decade ago, after a Dartmouth study found that mortality from thyroid cancer remained stable although incidence rates rose.3
However, in 2014, Dartmouth researchers confirmed their earlier findings that the rise in thyroid cancer was not an epidemic of disease, but rather an epidemic of overdiagnosis.4 "Again," Hay said, "they demonstrated that almost all of the increased rates occurred with papillary cancer, whose age-adjusted rate increased by almost four-fold from 1975 to 2009.''4
Recently, researchers from the International Agency for Research on Cancer published data indicating that up to 80% of thyroid cancers in the U.S., Italy and France represented an overdiagnosis—finding cancers that would otherwise not cause symptoms or problems.5 This report prompted the ATA to issue a statement acknowledging overdiagnosis of ''indolent papillary microcarcinomas that will never result in symptoms or death, and which only rarely will enlarge or spread beyond the thyroid gland."2
Under the updated guidelines for Thyroid Carcinoma, fine needle aspiration is not required for tumors less than 1 centimeter that appear to be confined to the gland.6
Behind the New Thinking
In his presentation, Dr. Hay also reported on more than 1,300 patients who were diagnosed with papillary microcarcinoma, from 1935 to 2014, and underwent a variety of treatments. "After an average follow up of more than 15 years, only 4 patients, or 0.3%, had died from thyroid cancer, while almost a third of the cohort died of other causes."
"We again demonstrated that patients with PTC have normal life expectancy, and typically are cured by adequate tumor resection," he said. The extent of initial surgery ''did not affect locoregional recurrence rates." More surgery, however, did lead to more nerve and parathyroid damage, reported Dr. Hay.
Consider Active Surveillance
Active surveillance with curative intent (ASCI), Dr. Hay said, is ''a concept you will be hearing more about." The approach was described in the Lancet; the researchers concluded: "On the basis of these data, active surveillance with curative intent, in which active treatment is delayed until the cancer shows signs of significant progression to avoid side effects of treatment, should be considered in properly selected patients."7
Dr. Hay also has been studying another option in a small group of patients with small tumors--ultrasound guided percutaneous ethanol ablation--a technique he has used for decades for neck nodal metastases.
Consensus is not yet unanimous that less is better. However, ''the last couple of years have seen a big shift," said Michael Tuttle, MD, co-author of the Lancet paper, and clinical director of the endocrinology service at Memorial Sloan-Kettering Cancer Center, NY.7
Both physicians and consumers ''are starting to recognize that we can find little cancers that don't need to be treated immediately," said Dr. Tuttle. The concept of active surveillance is well accepted with prostate cancers, and should be the approach with PTC, as well. Yet, there is still pushback.
"Any time you have a paradigm shift, people don't like that. Pushback is good; But...far less now. “Dr. Tuttle is studying the use of active surveillance with curative intent in more than 300 patients with very low-risk thyroid cancer at Memorial Sloan-Kettering. Just a few years ago, he said, people were questioning the concept. "Now, most of the questions I get [after lecturing on the topic] is 'How do you do that?' or, which patients are appropriate?'''