Active surveillance, defined as regular monitoring until treatment is required due to disease progression, is generally preferred for low-risk prostate cancer patients older than 70 years. This is in part due to the negative physical sequelae resulting from surgical intervention, as well as the lack of survival benefit after treatment. In contrast, surgery is the standard of care in thyroid cancer, and active surveillance remains controversial. A review published in the journal JAMA Oncology outlined the similarities between thyroid and prostate cancers regarding surveillance, screening, and diagnosis, and the lessons that endocrinologists and thyroid surgeons can learn from the practice of active surveillance in a select group of prostate cancer patients.
Nearly half of thyroid cancer cases are identified as microcapillary thyroid cancers, which have close to a 100% survival rate and a close to 0% rate of distant metastasis. Similar to thyroid cancers, prostate cancers are low risk and are usually nonlethal. However, the younger age of patients with thyroid cancer compared with those with prostate cancer, and the relative safety of surgical treatments in each respective cancer type, have led to differing treatment methods for these malignancies.
While active surveillance is generally accepted for low-risk patients with cancer who are older than 70 years, it is still a controversial treatment strategy in individuals with thyroid cancer. “Active surveillance is an emerging treatment tool that makes sense for a select group of patients. There [are] excellent data from Japan, Korea, and the United States showing it to be an appropriate treatment modality,” said an author of the review, Allen S. Ho, MD, who is director of the head and neck cancer program and codirector of the thyroid cancer program at Cedars Sinai Medical Center in Los Angeles, California. “Active surveillance is appropriate for the type of thyroid cancer that is considered incidental,” said Dr Ho. This refers to cancers that are discovered as a result of imaging or surgery for other health-related reasons. “In many ways, these incidental cancers are not likely to cause harm. Those patients would be good candidates for active surveillance.”
Maria Papaleontiou, MD, assistant professor of internal medicine at the University of Michigan, Ann Arbor, sees active surveillance as promising. “It’s an attractive option in view of the excellent survival of patients with low-risk thyroid cancers and its added benefit of avoiding treatment complications.”
In patients with thyroid cancer, active surveillance has been controversial because surgery, which is the standard of care, is normally a safe procedure with relatively low side effects and toxicity. “Thyroid surgery tends to be fairly routine and [is an] outpatient [procedure], and it has a low incidence of complications, which tend to be fixable,” explained Dr Ho.
Patients with prostate cancer may be more willing to undergo active surveillance than patients with thyroid cancer because in the former, survival does not improve with intervention and patients face a higher chance of adverse consequences from current treatments. “With prostate surgery, the effects may be temporary, but they could also be permanent. For instance, patients may not be able to [maintain] an erection or ejaculate after surgery,” Dr Ho explained.
Several challenges have to be overcome before active surveillance becomes widely implemented for monitoring thyroid cancer patients. “At this time, we do not have enough data to define and streamline the active surveillance process. [It’s not clear] how long we should be following patients, or how often we should be performing neck ultrasounds. Additionally, physician and patient worry about missed cancer progression may be a significant obstacle in electing active surveillance as an option,” says Dr Papaleontiou.
Given the risks, physicians need to educate their patients on the positive and negative implications of choosing active surveillance. “Sometimes our biases and philosophies will sway the patient one way or the other and it’s our obligation to provide the patient with the full menu of options that are appropriate for them,” said Dr Ho. Physicians can also reassure patients by establishing stricter selection criteria for deciding who is a good candidate for active surveillance, as well as more thorough monitoring protocols and lower thresholds for intervention. These measures could encourage more patients and physicians to consider active surveillance for thyroid cancer.
- Ho A, Daskivich T, Sacks W, Zumsteg Z. Parallels between low-risk prostate cancer and thyroid cancer. JAMA Oncol. doi: 10.1001/jamaoncol.2018.5321