Early Detection of Cancer is Crucial for Survival — Always True?
It can be a disquieting moment for a patient. A lump or bump is found on their neck. It is a thyroid nodule. Is it cancer? Many of those patients will probably want to get a biopsy as soon as they can. While biopsy makes sense for some patients, new scientific data tells us, it might not be the best option for all.
What is Thyroid Cancer?
Thyroid cancer is a disease in which malignant cells form in the tissues of the thyroid gland. Thyroid nodules are common but usually are not cancer.
Thyroid cancer is the most common endocrine malignancy. The vast majority of patients, more than 90%, are diagnosed with differentiated thyroid carcinoma (DTC). “Differentiated” means that the tumor cells still look similar to normal thyroid gland cells and behave similarly to normal cells. Among the thyroid cancer patients,
- between 85–90% depending on region and age groups have papillary thyroid carcinoma (PTC),
- 4.5% follicular thyroid carcinoma, and
- 1.8% Hurthle cell carcinoma. The remaining cases are diagnosed with
- medullary thyroid carcinoma (1.6%) or
- anaplastic thyroid carcinoma (0.8%).
Papillary thyroid cancer (PTC) and follicular thyroid cancer are well-differentiated tumors that in most patients grow slowly, can be treated, and can usually be cured. Poorly differentiated and undifferentiated tumors (anaplastic thyroid cancer) are less common. These tumors grow and spread quickly and have a poorer chance of recovery.
Particularly, the detection of papillary thyroid carcinoma (PTC), the most slowly growing tumor type, has led to a continuing increase in the number of thyroid cancers diagnosed during the last decades.
Thyroid Cancer Pandemic Started In 1980s
Since the 1980s, new diagnoses (“incidence rates”) of thyroid cancer have increased rapidly in most countries and regions, whereas the number of patients who died from thyroid cancer (“mortality rates”) have remained relatively stable or even declined.
This contradictory phenomenon has attracted widespread attention. The use of ultrasound to examine the thyroid in the 1980s, the introduction of fine-needle aspiration biopsy techniques in the 1990s, and the addition of new diagnostic imaging modalities (e.g., computed tomography, magnetic resonance imaging, and PET) in the 2000s have enabled detection of more and more even very small thyroid cancers in clinical practice.
Consequently, the number of detected thyroid carcinomas has nearly tripled in the United States since 1975, from 4.9 to 14.3 people out of 100,000. Interestingly, the increase in women was almost four times greater than in men. Similar data come from European registries. For example, in Switzerland, the incidence of thyroid cancer increased from 5.9 to 11.7/100,000 in women and 2.7 to 3.9/100,000 in men. The most spectacular data come from South Korea, where thyroid cancer incidence changed in women from 10.6/100,000 in 1996 up to 111.3/100,000 in 2010 — an elevenfold increase. Currently, thyroid carcinoma is the most common cancer in Korean women and the second most common cancer in females living in the UAE. However, this phenomenon is driven by the low-risk papillary thyroid carcinoma (PTC), while the number of other histological types of thyroid cancer remains stable.
A recent study conducted by the International Agency for Research on Cancer (IARC) provides a comprehensive analysis of thyroid cancer across more than 60 countries on five continents. In this study the researchers found that overdiagnosis accounts for a large proportion of the new diagnoses of thyroid cancer and that overdiagnosis has become a large problem worldwide. According to this study, more than 1.7 million people may have been overdiagnosed with thyroid cancer in 2013–2017 in 63 countries. Why should a sensitive early detection of a cancer be wrong? And what is ment by “overdiagnosis”?
Overdiagnosis? Should Not All Cancers Be Detected?
As we try more and more to pick up the early signs of disease, and as technology can see ever-smaller potential “abnormalities” in our bodies, we are diagnosing and treating some things that would never have gone on to cause us any problem if they were left alone.
Overdiagnosis happens when you get a diagnosis that ends up causing you more harm than good. Overdiagnosis can lead to aggressive treatments, physical and psychological harms, and financial burdens for individuals and health-care systems.
With thyroid cancer, small tumors are being discovered incidentally in people who don’t have any cancer symptoms but who were being tested for some other reason or have undergone a cancer screening program. Although there have been big increases in the numbers of people being diagnosed with thyroid cancer in recent years, no change in the number of people experiencing bad outcomes or death from their thyroid cancer has been observed. Therefore, researchers concluded that a proportion of those people have been overdiagnosed.
What Harm Comes From Thyroid Cancer Overdiagnosis?
The main harm caused by thyroid cancer overdiagnosis is overtreatment, which happens when you get a treatment that wouldn’t have been necessary and won’t help you. The most common treatment for people who receive a diagnosis of thyroid cancer is surgery to remove all or part of the thyroid gland. As a result of that surgery, it’s common that you have to take lifelong medication, and in rare cases there are complications of surgery, including damage to your voice.
Other harms of overdiagnosis and overtreatment of thyroid cancer may include emotional distress, increased anxiety, depression, insurance difficulties, and unneeded financial costs.
How to Deal With Thyroid Cancer (Over)Diagnosis?
Part of the challenge with thyroid cancer diagnosis or overdiagnosis is trying to work out which cancers will go on to cause harm, and which won’t.
Decrease Testing: One way to reduce overdiagnosis is to decrease the testing of people who don’t have any symptoms, to try to reduce the numbers diagnosed with the very small thyroid cancers that are highly unlikely to ever grow or cause harm.
A scientific anaylsis of Catherine Jensen and colleagues from the University of Wisconsin, US, titled “From Overdiagnosis to Overtreatment of Low-Risk Thyroid Cancer” dealed with attitudes and beliefs of doctors and their patients. Doctors described that the process commonly starts with incidental discovery of a thyroid nodule on imaging, with biopsy of the nodule as a reflexive action. The subsequent cancer diagnosis was seen as an event that “opens Pandora’s box” and often provokes a strong instinctive, culturally rooted need to proceed with surgery — specifically total thyroidectomy. Consequently, most doctors felt that it is easier to prevent overdiagnosis than overtreatment and recommended strategies such as improving guideline adherence and resetting patients’ expectations and engaging in patient education.
Michael Tuttle, MD, of Memorial Sloan Kettering Cancer Center, New York City, told Medscape Medical News about his experineces with PTC patients: Some patients will mistakenly think any cancer diagnosis is a likely death sentence, meaning they should rush to get aggressive treatment. Some patients express regret about having learned that they have low-risk thyroid cancer, Tuttle said. “Over the last 5 years, it’s not uncommon for patients to ask me, ‘Is this one of those that needs to be treated now, or is this one of those that we wish we would have never found?’.”
Consequently, the American Thyroid Association (ATA) guidelines indicate that thyroid nodules less than 1 cm should not be biopsied, nodules 1 cm to 1.5 cm should be biopsied only when features concerning for a malignant tumor exist.
“Active surveillance” option for selected patients: Is it really possible or advisable to wait when there is cancer? What does science tells us?
In the 1990s, a group of Japanese surgeons at Kuma Hospital began to offer observation alone to their patients with papillary thyroid microcarcinomas, defined as tumors smaller than 1 cm. Overall, 70% of patients experienced no change or a decrease in size over a mean of 4 years of follow-up.
A subsequent study found that the detection rate of new lymph node metastases during active surveillance was comparable to the recurrence rate following upfront surgery — which means, surgery didn´t provide a benefit over active suveillance.
Indeed, a careful review of the thyroid ultrasound, physical examination, and a discussion with the patient allow doctors to identify which patients are the best candidates for active surveillance. When patients with small tumors are eligible for active surveillance, the vast majority of those tumors remain stable or grow very slowly over five to 10 years. Only a few tumors do gradually enlarge during the first year or two of follow-up. Patients are provided with treatment later, if or when it really becomes necessary.
Patients enrolled in the active surveillance program usually will start having ultrasounds and exams every six months. If there is no change after two years, they will only need to come in once a year. Once these small tumors are shown to be stable for five years, ultrasound examinations are done every two to three years.
The American Thyroid Association (ATA) recommends that papillary thyroid cancer (PTC) nodules 1 cm or less should be managed with active surveillance or, if necessary, only by a partial removal of the thyroid gland (lobectomy) instead of complete removal of the thyroid gland (total thyroidectomy) or radioactive iodine (RAI) treatment.
Fear is No Good Advisor, Knowledge is!
If you have been told, there is a node in your thyroid gland, fear about cancer is only natural. While early detection requires fast therapeutic action for several highly aggressive cancer types, medical research has revealed that for some other cancer types this is not the case. This includes a small nodule of a highly differentiated papillary thyroid carcinoma that causes no symptoms and is found by chance.
Knowing that this tumor is unlikely to grow significantly, if at all, and will never cause harm, may prevent you from taking actions that carry risks to your health, unlike the tumor. Every operation and every anesthetic has risks, even if they are rare. Surgically removing the tumor, especially if it is done by completely removing the thyroid gland, also takes away your ability to produce an important hormone, requiring lifelong hormone replacement with medication.
It is wise to accept the risks of surgery when an aggressive, fast-growing tumor needs to be removed. On the other hand, it is not recommended if the operation involves more damage and risks than a tumor that grows slowly or not at all. If you can control your anxiety through knowledge, waiting is the more sensible decision.
The doctors Maria Papaleontiou and Megan Haymart from the University have come to a conclusion in their article “Too Much of a Good Thing? A Cautionary Tale of Thyroid Cancer Overdiagnosis and Overtreatment”:
“In the end, we should all be cognizant that too much of a good thing may not be a good thing at all when it comes to low-risk thyroid cancers.
We should all strive to uphold our promise: first, do no harm.”
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a contribution of Dr. Gabriele Stumm
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