Active Surveillance Confirmed as Best for Low-Risk Thyroid Cancer

Pam Harrison

December 20, 2017

Active surveillance rather than immediate surgery for low-risk papillary microcarcinomas (PMCs) of the thyroid has again been endorsed by leaders in the field, because they say only a fraction of these low-risk tumors progress and when they do, salvage surgery appears to be uniformly successful.

PMCs are defined as a papillary thyroid carcinoma of 10 mm or less and are felt to account for at least 50% of all thyroid cancer diagnoses in recent series.

"The vast majority of PMCs are asymptomatic tumors lacking aggressive features [and are] detected incidentally by imaging studies or thyroid-screening studies," Akira Miyauchi, MD, department of surgery, Kuma Hospital in Kobe, Japan, and colleagues say in their review in Thyroid.

In this, they detail their experience of watchful waiting in some patients.

"In both [of our] series, none of the patients who underwent rescue surgery after progression signs were detected showed significant recurrence or died of papillary thyroid carcinoma (PTC)," they note.

"[So] active surveillance of low-risk PMC can be the first-line management. Educating physicians, surgeons, patients, and the public about how active surveillance of low-risk PMCs can be an excellent management modality is important," they conclude.

The American Thyroid Association has also recently endorsed active surveillance as an alternative to traditional treatment in carefully selected patients.

Tumors Least Likely to Enlarge or Metastasize in Those Over 60 Years of Age

Active surveillance of papillary microcarcinomas of the thyroid was offered as an option to appropriate patients by the Kuma Hospital in Kobe and Tokyo's Cancer Institute Hospital in the mid-1990s.

"The question of whether immediate surgery or active surveillance is better for managing low-risk PMC patients is important," Dr Miyauchi and colleagues emphasize

The researchers summarized their experiences from Japan.

In the Kuma Hospital, of 2153 patients with low-risk PMCs, 1179 (55%) chose active surveillance; in these patients, only 8% of tumors grew by 3 mm or more over 10 years of observation, and only 3.8% of patients had evidence of novel node metastasis at the same time point.

This also showed that tumors are least likely to enlarge over time or metastasize in patients 60 years of age and older, as the researchers observe.

Of the active-surveillance patients, 94 underwent conversion thyroid surgery for various reasons, including the patient's change of mind. Although one of these patients had a local recurrence requiring salvage surgery, the 94 patients were free of disease

The 974 (45%) of patients who chose immediate surgery had significantly higher incidences of unfavorable events than those who chose active surveillance. These included temporary vocal-cord paralysis, permanent or temporary hypoparathyroidism, need for levothyroxine substitution, and a surgical neck scar.

Postsurgery, five of the 974 patients had local recurrence that was successfully treated by salvage surgery. The remaining patients were alive without evidence of disease, but another five patients died of other causes.

The total cost of immediate surgery, including the costs for salvage surgery and postoperative care for 10 years, was 4.1 times the total cost of 10-year management by active surveillance.

In the Tokyo Cancer Institute series involving 230 patients with 300 lesions, only 7% of patients had enlargement of their tumor at 10 years while novel node metastases were detected in only 1% of the group overall.

Most Patients Will Not Ultimately Require Surgical Intervention

"One may argue that active surveillance only delays surgical intervention," the researchers observe. But based on patients age, studies suggest that just under half of patients in their 20s will progress, as will about one-quarter of those in their 30s.

About one-fifth of those in their 40s will similarly progress, as will about 10% of patients in their 50s and 60s. By the time patients reach the age of 70, only 3.5% of them experience disease progression.

These estimates indicate that ≥ 50% of patients in their 20s and approximately 75% of those in their 30s would not require surgical intervention during their lifetimes, and the vast majority of patients in their 40s or older would not require surgical intervention during their lifetimes either, the team argues.

The authors also rechecked all the records of female patients 50 years of age and under with PMCs who were followed with active surveillance at the Kuma Hospital to see if this was an appropriate strategy for patients planning pregnancy.

Only 8% of women with low-risk PMCs had evidence of tumor growth of 3 mm or more based on measurements done before they became pregnant and following childbirth.

"Thus, young females with low-risk PMCs and the possibility of future pregnancies do not need to be excluded from active surveillance," investigators state.

"If their tumors enlarge, rescue surgery after delivery would not be too late," they add.

Active Surveillance Should Be First-Line Treatment Option

"In the authors' opinion, active surveillance is more appropriate for triaging PMC that may have aggressive behavior, and a rescue surgical treatment should be done as the second-line of therapy for PMCs that may grow," the researchers conclude.

At least in Japan, patients who decide on active surveillance undergo ultrasound 6 months after they are diagnosed with PMC and then once a year thereafter.

Accurate ultrasonographic findings obtained by a skilled sonographer are necessary for evaluating low-risk PMC, however, they stress. A system for the follow-up of patients at outpatient clinics is also mandatory, with a recall system by mail or another form of contact, necessary for patients who do not comply with regular checkups.

If on ultrasound, operators detect a suspicious node, a fine-needle aspiration biopsy is done and tested to ascertain whether the nodes are metastatic or not, the authors note.

They recommend rescue surgery if tumors have increased by at least 3 mm.

On the other hand, if a patient wants to continue with active surveillance, "it can be continued until the tumor size reaches 13 mm," investigators suggest.

"[But] cases with newly appearing lymph-node metastasis are strong candidates for rescue surgery," they conclude.

The authors had no relevant financial relationships.

Thyroid. Published online September 22, 2017. Article

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