Across many countries, thyroid cancer has been increasing faster than most other cancers. This trend has raised major concerns among health experts, especially as new cases continue to grow even with medical advancements. Understanding why this rise is happening can help us make sense of both the risks and the changes happening in our environment and healthcare systems.
Thyroid Cancer: A Quick Look
The thyroid is a small gland located in the front of the neck. It releases hormones that control heart rate, temperature, weight, and many other important body functions. Thyroid cancer develops when the cells inside this gland grow uncontrollably and form a tumour.
Most thyroid cancers are treatable, but the rising numbers remain worrying. In the United States, for example, cases more than tripled between 1980 and 2016. This pattern has been in other regions as well.
Is Better Diagnosis a Major Reason?
For many years, experts were unsure why thyroid cancer cases were climbing so rapidly. There were no major nuclear disasters or large-scale radiation events to explain the sudden rise. But one major shift did occur: medical technology became more advanced.
During the 1980s, doctors started using thyroid ultrasound scans, which could detect very small growths that would have previously gone unnoticed. In the 1990s, fine needle aspiration biopsy also became common, allowing doctors to test tiny nodules for cancer.
This led to the discovery of many small tumors that may never have caused symptoms or harm. At the same time, deaths from thyroid cancer remained stable, further supporting the idea of overdiagnosis.
South Korea experienced a dramatic spike in thyroid cancer rates after introducing widespread screening. When screening was reduced, cases dropped again.
These findings made it clear that better detection played a major role in rising numbers.
Why Overdiagnosis Is Not the Only Cause
Even though advanced screening explains part of the rise, it does not explain everything. Middle-income countries without strong screening programs are also showing rising thyroid cancer rates. Larger and more advanced tumors are being diagnosed more often too, which suggests the increase is not only due to finding small harmless cancers.
Some studies have also found that deaths from thyroid cancer are rising slightly in certain countries, meaning something more serious may be happening.
Possible Causes Behind the Real Increase
1. Obesity and Metabolic Health
One strong factor linked to thyroid cancer is obesity. Research shows:
- People with a high BMI have over 50% higher risk of developing thyroid cancer
- Obesity is also linked to more aggressive tumour types
- Thyroid dysfunction and high TSH levels are more common in people with excess weight
Scientists believe inflammation, insulin resistance, and hormonal changes may play a role.
2. Radiation Exposure from Medical Scans
CT scans and X-rays have become far more common, especially in children. These scans expose the thyroid to higher levels of ionizing radiation. Studies estimate that thousands of future thyroid cancer cases may be linked to CT scan exposure alone.
Because children’s thyroid glands are more sensitive, early radiation exposure may increase lifetime risk.
3. Environmental Chemicals
Some scientists are studying endocrine-disrupting chemicals found in household items, food packaging, cookware, and even firefighting foam. These chemicals can interfere with hormones. Substances like PFOA and PFOS may be linked to thyroid issues, though the evidence is still not clear.
4. Trace Elements and Natural Factors
Thyroid function depends on small amounts of certain minerals. Some island nations show unusually high thyroid cancer rates, and environmental elements like cadmium, zinc, vanadium, and volcanic minerals may be involved. However, more research is needed before confirming a direct connection.
A Multifactorial Problem
Most experts now agree that no single cause explains the rise. Instead, it is likely a mix of factors:
- Better detection
- Obesity
- Radiation exposure
- Environmental chemicals
- Genetic vulnerability
- Hormonal and dietary changes
This combination can lead to both small tumours being detected more often and more aggressive cancers increasing in number.
The rise in thyroid cancer remains a complex global issue, but understanding these factors can help us improve prevention and shape better health policies.
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