When it comes to cancer, thyroid cancer is considered to be highly survivable condition. Unfortunately, this fact has overshadowed much of the danger associated with the condition. Perhaps the most overlooked and insidious aspect of thyroid cancer is that it significantly increases the risk of developing a second primary cancer.
It is often the case that thyroid cancer patients are not informed of this potential threat. Those impacted by thyroid cancer must be made aware not only of the immediate risks of the condition but the danger that remains after it has been treated.
The Function of the Thyroid
The thyroid is a small butterfly-shaped gland located in the neck that influences cellular activity through the productions and regulation of hormones. Thyroid cancer can develop in either of the gland’s two lobes and may spread through its entirety. If the malignancy is recognized before it has advanced to other regions, such as the lymph nodes, a patient may elect to have a thyroidectomy. This surgical procedure involves a total or partial removal of the thyroid gland thereby eliminating cancerous tissue.
Overview of Thyroid Cancer
Thyroid cancer is the tenth most common form of cancer. The occurrence of thyroid cancer has been on the rise in the United States for the past 30 years. In 2015 alone, nearly 62,450 Americans were diagnosed with thyroid cancer while 1,950 deaths were attributed to the disease. Worse still, experts believe that rates of thyroid cancer will continue to grow in the coming years.
There are four distinct types of thyroid cancer: papillary, follicular, medullary, and anaplastic.
Papillary thyroid cancer is the most common and has the greatest survival rate. When left untreated, it is likely to spread to the lymph nodes. As a differentiated thyroid cancer, papillary thyroid cancer causes afflicted cells to appear and act like healthy thyroid cells.
Follicular thyroid cancer is less common but more aggressive than papillary thyroid cancer. This form also has a relatively high cure rate but typically spreads to other systems such as the lungs, bones, and skin. Follicular, like papillary thyroid cancer, is a differentiated form making diagnosis more difficult.
Medullary thyroid cancer is unique in that it originates in C cells rather than follicular cells, which are responsible for hormone production. This strain of thyroid cancer is likely to spread to the lymph nodes and is connected to hereditary risk factors.
Anaplastic thyroid cancer is the least common but most dangerous form of thyroid cancer because it is very likely to infect other organs throughout the body. Whereas thyroid cancer in general is usually seen in younger individuals, anaplastic thyroid cancer often occurs in older populations.
The Hidden Dangers of Thyroid Cancer
Thyroid cancer possesses a particularly insidious trait that is frequently overlooked. According to research presented in Cancer Epidemiology, Biomarkers & Prevention those who survive thyroid cancer have an increased risk of developing a secondary malignancy. Another study published in the Journal of Clinical Endocrinology and Metabolism further supports this claim by presenting findings that suggest patients who survive thyroid cancer are 30 percent more likely to develop a secondary cancer when compared to the general population. Specifically, thyroid cancer survivors are more likely to develop cancer in one or more of the following areas:
- Salivary Gland
- Parathyroid Gland
- Small Intestine
- Soft Tissue Carcinoma
- Female Breast
Other studies show that the risk of thyroid cancer patients developing cancer in the adrenal gland, kidney, and prostate as well as non-Hodgkin’s lymphoma and non-melanoma skin cancer are greatest just after treatment is completed. The most common forms of secondary cancer among thyroid cancer patients is in the salivary gland and kidneys.
Uncovering the Connection
It is clear that thyroid cancer patients have an increased risk of developing future malignancies. However, there is uncertainty as to why. Experts have conducted a significant amount of research to discover the link between thyroid cancer and greater risk of malignancy. This work has led to multiple theories.
Mutually causative factors between thyroid and other forms of cancer, such as hormone dysfunction or imbalance, may play a role in the connection between thyroid cancer and future malignancies. Studies have found that increased exposure to thyroid-stimulating hormones, which is often experienced by thyroid cancer patients.
Increased exposure to radiation is another possible cause. It has been shown that radiation treatments may increase the risk of lung and esophageal cancers, blood cancers, and sarcomas. Because radioactive iodine is a common practice for treating thyroid cancer it is possible that the increased exposure to radiation may prompt the development of a second primary cancer in thyroid cancer patients.
Other factors that experts believe contribute to the development of thyroid cancer may also increase the risk of future malignancies. These risk factors include:
- A family history of Hashimoto’s or other thyroid disease
- Age (thyroid cancer is most frequently seen in people between the ages of 20 and 55)
- Being a woman (approximately 75% of thyroid cancer cases affect females)
- Exposure to radiation
- Hereditary conditions such as Gardner syndrome, Cowden disease, and adenomatous polyposis
- Iodine deficiency
Combat Cancer by Raising Awareness
Although thyroid cancer is highly survivable, the increased risk of future malignancy makes it an exceptionally threatening condition. Being aware of this threat is important as it primes patients to be on the lookout for future cancer developments. Due to the increased risk of malignancy thyroid cancer survivors should always attend periodic check-ups and regular cancer screenings to improve their odds of catching malignancies early in development. Recognizing cancer in the early stages significantly improves treatment and recovery. Protect yourself and others by spreading the word and increasing awareness of the increased risk of malignancies associated with thyroid cancer.
1. Medical News Today. Thyroid and breast cancer survivors at risk of the other malignancy. Updated February 2016. https://www.medicalnewstoday.com/articles/306121.php
2. American Cancer Society. Cancer Facts & Figures 2018. Updated January 2018. https://www.cancer.org/cancer/thyroid-cancer/about/key-statistics.html
3. Aaron P, Brown J, et al. “The Risk of Second Primary Malignancies up to Three Decades after the Treatment of Differentiated Thyroid Cancer.” Thyroid. 2007; 93 (2): 504-515. doi: 10.1210/jc.2007-1154
4. Kim C, Bi X, et al. “The risk of second cancers after diagnosis of primary thyroid cancer is elevated in thyroid microcarcinomas.” Thyroid. 2013 May;23(5):575-82. doi: 10.1089/thy.2011.0406. Epub 2013 Apr 18.
5. Sandeep, Thekkepat C. et. al. “Second Primary Cancers in Thyroid Cancer Patients: A Multinational Record Linkage Study, J Clin Endocrinol Metab 2006 91: 1819-1825; first published February 14, 2006 as doi:10.1210/jc.2005-2009