Papillary thyroid cancer is the most common type of thyroid cancer, accounting for 70% to 80% of all thyroid cancer diagnoses. With an overall thyroid cancer incidence rate of about 11 per 100,000 people per year, papillary cases make up the vast majority. Despite rising numbers over the past several decades, it remains one of the most treatable cancers, with a five-year survival rate of 99.9% when caught before it spreads beyond the thyroid.
Incidence Rates and Who Gets It
Papillary thyroid cancer is roughly three times more common in women than in men. The overall age-adjusted incidence rate for thyroid cancer is about 16.3 per 100,000 women compared to 5.7 per 100,000 men. In women, the rate rises sharply at the start of the reproductive years and peaks between ages 40 and 49. In men, the peak comes later, between 60 and 69.
Though women are diagnosed far more often, men tend to have more aggressive disease at the time of diagnosis. The reasons for the gender gap aren’t fully understood, but hormonal factors during reproductive years are a leading hypothesis.
In children and teenagers, thyroid cancer is much rarer. Among 15- to 19-year-olds, the incidence is about 1.8 per 100,000 per year. Younger children are diagnosed even less frequently, though pediatric rates have also been climbing over time.
Why Cases Have Been Rising for Decades
The number of papillary thyroid cancer diagnoses has increased substantially since the 1970s, and the trend continued through at least 2021. Global data shows thyroid cancer incidence rose by about 20% between 1990 and 2013 alone, with researchers in the U.S. and Australia describing the increase as exponential during certain periods.
A major driver of this rise is better detection rather than a true epidemic. Widespread use of neck ultrasounds, CT scans, and other imaging has uncovered tiny thyroid nodules that would have gone unnoticed in previous decades. Autopsy studies help put this in perspective: when researchers examine thyroid tissue from people who died of unrelated causes, they find small papillary thyroid cancers (under 1 cm) at rates ranging from about 3% to 36% depending on the population studied, with an average of 11.5%. In other words, a significant fraction of people carry tiny papillary cancers in their thyroid without ever knowing it or being harmed by them.
This doesn’t mean the entire increase is an artifact of screening. Some evidence suggests that larger, clinically significant tumors have also become more common. But the sharpest rise has been in small cancers found incidentally, which has fueled an ongoing debate about overdiagnosis.
Known Risk Factors
The most well-established risk factor for papillary thyroid cancer is exposure to ionizing radiation, particularly during childhood. The risk increases measurably once the radiation dose to the thyroid exceeds about 50 to 100 milligray. Above that threshold, risk rises in a roughly linear fashion with increasing dose. Children exposed to a dose of 1 gray to the thyroid have a relative risk roughly 5 to 8.5 times higher than unexposed children.
Radiation exposure can come from medical treatments (such as radiation therapy to the head or neck during childhood) or from environmental events like nuclear accidents. The Chernobyl disaster provided some of the clearest evidence: children in heavily contaminated areas of Ukraine developed papillary thyroid cancers driven by specific genetic rearrangements linked to radiation damage.
Beyond radiation, other risk factors include a family history of thyroid cancer, certain inherited genetic syndromes, being female, and iodine deficiency. Obesity has also been associated with a modestly increased risk, though the mechanism isn’t well established.
Survival Rates by Stage
Papillary thyroid cancer has some of the highest survival rates of any cancer. Based on data from the National Cancer Institute covering 2015 through 2021:
- Localized (confined to the thyroid): 99.9% five-year survival
- Regional (spread to nearby lymph nodes): 98.1% five-year survival
- Distant (spread to other parts of the body): 50.2% five-year survival
Most people are diagnosed at the localized or regional stage, which means the overwhelming majority can expect an excellent outcome. Even when papillary thyroid cancer spreads to lymph nodes in the neck, which is relatively common with this type, survival remains very high.
Distant spread is uncommon and changes the picture significantly, but it still represents a small fraction of all cases. Factors that increase the likelihood of aggressive disease include older age at diagnosis, larger tumor size, and being male.
Recurrence After Treatment
One concern for people treated for papillary thyroid cancer is whether it will come back. In a large study of more than 4,000 patients followed for an average of nearly five years, the recurrence rate was 4.3%. Most recurrences showed up in lymph nodes in the neck rather than as distant spread to other organs.
The median time to recurrence was about 57 months, or just under five years. However, some recurrences were detected more than 20 years after initial treatment, which is why long-term monitoring with periodic neck ultrasounds and blood tests is standard practice. The slow growth pattern of papillary thyroid cancer means that even recurrences are generally treatable, though they do require additional intervention.
What “Common” Really Means in Context
Papillary thyroid cancer occupies an unusual space in oncology. It is common enough that most people know someone who has had it, and diagnoses continue to rise. At the same time, it is rarely fatal. For many patients, particularly those with small tumors confined to the thyroid, treatment is straightforward and the prognosis is excellent.
The high prevalence of tiny, undetected papillary cancers found in autopsy studies suggests that many of these tumors would never cause symptoms or shorten a person’s life. This has led some medical guidelines to recommend active surveillance rather than immediate surgery for very small, low-risk papillary thyroid cancers. The goal is to avoid unnecessary treatment for cancers that may never progress, while still intervening promptly for those that show signs of growth or spread.