Other than astrologers looking for an emotionally deep love affair, no one wants to be told that a cancer has been found. This is especially true for endocrine cancers, which occur in organs most people haven’t even heard of and can have complex hormonal effects.
Cancer of the thyroid, a gland located at the front of the throat that looks like a small fleshy butterfly, is the most common endocrine cancer. In 2022, thyroid cancer comprised 2.5% of all cancers diagnosed in Australia.
While the risk is higher for people who have been exposed to radiation, have certain genetic mutations, are obese, or deficient in iodine, rates of thyroid cancer have been steadily increasing in all populations over the past few decades.
Some researchers argue that this is due to better scans and more testing, rather than more people actually developing cancer. Improvements in technology mean that extremely small growths can now be detected, and are often incidentally discovered during unrelated scans on the head and neck. Criteria for what counts as a cancer have also changed.
Studies have shown that benign thyroid growths, called nodules, are incredibly common, and the majority of people develop them as they age. Some of these turn out to be cancerous, but still might not be worth worrying about. A tiny, slow-growing tumour that might cause trouble in 50 years isn’t a huge problem if you’re already 80.
Given this, it would be easy to think that thyroid cancer is like taking your piece of cake for a walk in the park. However, some thyroid cancers can be much more than an annoyance – they can be a real pain in the neck.
Gild by association
Dr Matti Gild, multi-award-winning Chair of the Thyroid Cancer Research Group at the University of Sydney, has had her finger on the pulse of thyroid cancer for 13 years. Her group works on translational research – turning interesting research findings and lab discoveries into real-world treatments for patients.
Matti is currently overseeing over 15 studies for every aspect of thyroid cancer – from the best way to transition kids from children’s services to adult services, to the best timing for anti-cancer drugs, to developing an AI to analyse diagnostic images.
She warns that while thyroid cancer has the reputation as the fluffy bunny of oncology, some variants are not so docile.
A papillar tiger
Papillary thyroid cancers are named for the knobbly papilla that characterise their bumpy shape. They’re the most common type of thyroid cancer, and usually the least worrisome. They generally form in the follicular cells of the thyroid, which are responsible for the production and storage of hormones. While they can metastasise and spread to other areas, these cancers usually keep a low profile, growing very slowly and remaining confined to the thyroid gland for years, or even decades.
This means that in some cases of low-risk papillary thyroid cancer, doctors and patients can take an ‘active surveillance’ or ‘watchful waiting’ approach. This basically means keeping an eye on the tumour, swooping in if it looks like it might turn nasty. As surgery for thyroid cancer can be very hard on the body, sometimes leaving patients with long-term side-effects, some doctors argue that the best thing to do for the patient’s quality of life might sometimes be leaving the cancer alone for as long as possible. Matti’s team has helped to develop an online tool to help doctors and patients make this decision.
While it sounds like it could be stressful, one study showed that people who chose the watchful waiting approach didn’t feel any more anxious than people who chose to have surgery. Some doctors have even suggested calling papillary thyroid cancers “occult papillary tumours” to destigmatise the growths – though it’s unclear whether the implication of witchcraft is any less nervewracking.
However, there are always exceptions, which is why Matti’s team is also looking at the best way to treat high-risk papillary thyroid cancers. These tumours usually require removal of the thyroid gland and a course of radioactive iodine. One of the team’s studies will investigate whether high doses or low doses of radioactive iodine work best for eradicating this particular cancer.
Necks on the agenda
Many of the studies run by Matti’s team relate to targeting the right kinds of cancers with the right kinds of treatment.
Radioactive iodine is used to finish off many types of thyroid cancer after surgery removes the bulk of the tumour, but Matti’s team is looking at its effectiveness for particular kinds of tumours: those related to mutations in the gene that encodes BRAF proteins, and those characterised by a particular type of cancer cell called a Hurthle cell. These kinds of tumours have a reputation for shrugging off radioactive iodine, but the team’s research hopes to find out for sure.
Other studies hope to pinpoint the reasons why some tumours might be resistant to certain kinds of drugs. By doing a PET scan to watch the tumour at work, or investigating a tumour’s genome, the researchers can pinpoint the exact features or genes that hinder treatment.
Genetics are particularly important for medullary thyroid cancer. This aggressive form of thyroid cancer occurs in the parafollicular cells, which help to regulate the body’s level of calcium. It’s also hereditary, though some also occur spontaneously. The genetic processes that lead to medullary tumours are well-understood, but it’s led researchers to wonder if other kinds of thyroid cancer run in families too.
However, Matti’s team isn’t all about the test tubes and microscopes. One of their larger studies is a survey given to all patients about their experience at the centre, helping to improve their service. This complements the group’s ethos of co-design – working with patients to design studies that centre patient experience, and focus on what they want out of their own treatment.
A Gilded cage
If cancer is a particularly awful zoo, then thyroid cancer is the terrible butterfly house. In the same way that there are many sorts of butterflies, there are also many types of thyroid cancers, all with their own origins, behaviours, and vulnerabilities. As the zookeeper, Matti’s job is to study these entities to understand how they work – and make sure visitors to the zoo make it out without too much trouble.
