does all thyroid cancer need surgery?
There are mixed messages in the media about thyroid cancer. On one hand we hear that thyroid cancer has shown a dramatic increase in cases worldwide. In Australia currently, of all malignancies documented in the national cancer registries, thyroid cancer is the most rapidly increasing in females. On the other hand, large international studies have shown that the death rate from thyroid cancer has not increased significantly despite the documented rapid increase in incidence of the disease. This discrepancy raises the question of whether the type of cancer that is being increasingly detected is actually a potentially lethal one at all. Are we just diagnosing tumours that would never have caused any problems if simply left alone?
The impact of this question is sufficiently newsworthy to have recently headlined in the New York Times Health Section (22 August 2016 )- “Got a Thyroid Tumor - Most Should be Left Alone”. In that article, Gina Kolata wrote … “the data in a new report on thyroid cancer was stunning. From 2003 to 2007 as many as 70 percent to 80 percent of women in the United States, France, Italy and Australia who were told they had thyroid cancer and who often had their thyroids removed actually had tumours that should have been left alone".
This has led to the recent major advance of “active surveillance” for papillary microcarcinomas in some selected cases. This approach was pioneered by the Kobe Thyroid Clinic in Japan and has now been incorporated into the American Thyroid Association (ATA) Thyroid Cancer Guidelines. The recommendations are based on the Kobe experience of over 2,000 cases of diagnosed papillary thyroid microcarcinoma followed up by surveillance for over 20 years. Active surveillance involves annual assessment with clinical examination, ultrasound and thyroid function tests, with referral for surgery only if there is “progression” of the cancer. This is defined as an increase in the size of the nodule, or metastases into local lymph nodes. The Kobe experiences shows that only 8% of that entire group progressed with growth of the cancer and only 4% developed lymph node metastases. Importantly all of those patients responded to the delayed surgery and no patient in that series has ever died of thyroid cancer.
It is important to note however that active surveillance is only appropriate for selected patients, typically the elderly with ring calcified microcarcinomas. It is usually not an option for is young patients (<40 years) are more likely to progress and who face decades of surveillance and screening. In young patients, or those with infiltrative mocrocarcinomas, surgical resection is still the best option.