Thyroid Cancer: The Unique Cancer
The Unique Cancer
By Rita Banach, B.Sc., DCS, President, Thyroid Cancer Canada
Reprinted with permission and much thanks from Thry'vors News, Winter 2012/13, available at www.thyroidcancercanada.org
Just a decade ago, thyroid cancer was considered a rare cancer. Since then, the rate of incidence has had a steep incline for unknown reasons. The incidence of thyroid cancer worldwide is now estimated at 213,000 persons per year, making it the ninth most common cancer in women in the world(1). It is the fifth most common cancer in Canadian women and the most common cancer in young women. An estimated 5,600 new patients will be diagnosed this year in Canada(2).
Thyroid cancer is unique amongst cancers for many different reasons.
Generally speaking, cancer as a group of diseases affects older persons and more men than women. In contrast, thyroid cancer is a disease most often diagnosed in young women (defined as age 15-29 by the Canadian Cancer Society). It is the leading cancer in this group as almost 20% of all cancers diagnosed in young Canadian women are thyroid cancer(3).
Although only 21% of new thyroid cancer patients are male, women have an overall five-year survival ratio of 99% whereas it drops to a 94% cure rate in men(4). The reasons for these male-female differences are unknown.
Amongst all cancers, thyroid cancer has the widest range of possible outcomes based on the type initially diagnosed. It is divided into four main types or subgroups of disease. The vast majority of patients (85-95%) have a very curable form known as 'differentiated' (Papillary or Follicular). The cure rate for this type is excellent, especially in young women (near 100% cure rate for this segment). However, the rare type known as Anaplastic (1-2%) is opposite; having amongst the worst prognoses for any type of cancer. It is often fatal within months of diagnosis.
No warning signs
There are no known preventative actions -- including health or lifestyle changes -- to avoid being afflicted with the most common differentiated (DTC) type of thyroid cancer.
In its early stages, thyroid cancer usually has no warning signs or health side-effects. There are no cancer marker screening tests to warn of or lead to an initial diagnosis of microscopic DTC. At this time, there are only tests which can be conducted once a nodule becomes large enough to be apparent by other means and then be scanned and/or biopsied. Up to half the population has thyroid nodules and as many as 95% of these nodules are benign. Furthermore, the majority of those which are cancerous are slow-growing in nature. These factors have the potential to create a bias in medical priority delaying diagnosis. It is not unusual for patients to be told that based on the size and/or number of tumours confirmed after surgery, that they likely had thyroid cancer for 10 years or more prior to diagnosis.
Many patients begin their thyroid cancer journey at the point at which their nodule(s) became palpable (able to be felt). Despite the capacity for thyroid nodules to be noted by expert clinicians via physical examination, a neck check is an optional inclusion in a physical examination given by family doctors. To make matters worse -- and as incredible as it seems to most thyroid cancer patients -- TIME Magazine(5) published an article last year which claimed "that when it comes to lives saved, thyroid-cancer screening may be doing little or no good. In fact, it's probably mostly causing harm." This statement was made as part of the author's contention that most thyroid tumours diagnosed are "incidentalomas," a word coined to refer to tumours found accidentally while a patient is being scanned or reviewed for a different reason. The author also suggested that most thyroid cancer nodules are harmless. This assertion was based on studies(6) that contended that thyroid cancer's drastic increase rate is explained by accidental discoveries of small nodules (e.g. via neck scans for other reasons). However, the TIME Magazine author did not consider that this theory was subsequently disproven in at least three more recent studies(7). The newer studies provided data establishing that tumours of all sizes are being diagnosed and via various initiators, thus the rise in incidence is a significant trend of the last decade, unrelated to method of discovery.
Hurry up and wait
Wait times for diagnosis, as well as thyroidectomy surgery, vary from one province to another, but often are longer than optimal. Additionally, once surgery is complete, waiting to see an endocrinologist or other thyroid cancer specialist for lifelong follow-up may be equally lengthy or difficult to arrange.
In Ontario, for example, thyroid cancer surgery is given the fourth level of priority (longest allowed wait times) because the cancer is categorized as 'indolent,' meaning slow-growing. The Ontario Ministry of Health and Long-term Care posts the goal wait time for thyroid surgery as no longer than 84 days, but in mid-2012 reported an average wait of 97 days for thyroid surgery(8) (ranging from 28 days at Markham-Stouffville to 180 days at Ottawa Hospital).
With a current trend toward having thyroidectomy surgeries concentrated in centralized thyroid clinics, the level of care in terms of positive surgical outcome likely increases(9), but wait times may also increase. Waits of up to six months on surgical waiting lists have the potential of considerable consequences, especially in cases where patients additionally waited or were delayed significant periods of time to be diagnosed or to be assessed by an expert surgeon initially. This issue was reflected in a study(10) of urban/suburban/rural differences in initial diagnosis. According to the study of 3,500 thyroid cancer patients with differentiated forms of the disease (divided into three Ontario population groups: urban, suburban and rural), patients who lived outside the largest urban centre in the province (Toronto) tended to present initially with tumours larger than 2cm. If they lived in an area defined as rural, they presented with still larger tumours on average. As well, analysis of the data also found a significant gender gap vis-à-vis men presenting with larger tumours at the time of diagnosis.
Treatment determined by location
After surgery, there is diversity in the way thyroid cancer patients are "followed." In some regions, most patients are followed for life by an endocrinologist. In other areas, their care is led by an oncologist, nuclear medicine MD, surgeon, or family medicine doctor. Sometimes patients are followed initially by a specialist, who at some point in time "graduates" his/her patients; that is, informs them that they no longer in need of his/her expertise and can be thereafter followed by a family doctor. This element of variety adds to the diversity of treatment, follow-up protocols and attitudes.
A 2007 study(11), for example, highlighted some significant diversity of treatment and follow-up. In surveying more than 1,000 North American physicians who follow thyroid cancer patients (including practitioners representing the fields of endocrinology, nuclear medicine, general surgery, otolaryngology, paediatric endocrinology and internal medicine), the study found significant regional differences in opinion in regard to the need for radioactive iodine (RAI) treatment as an adjuvant treatment of the disease. The research found distinct east-west differences across the continent, and possible cultural differences with the highest rates of RAI use in Quebec. Also, those MDs with a hospital/university affiliation had a higher rate of RAI use, whereas surgeons as a group had a lower rate of RAI use. Additionally, the authors postulated that MDs have varying access to blood laboratories (i.e. the ability to test thyroglobulin; a cancer marker test) and/or imaging modality availability, according to their hospital affiliation and location.
Simple geography, therefore, has an effect on the course of diagnosis, surgery and of follow-up of thyroid cancer patients.
Had my surgery, had my treatment, now what?
Thus far, this article has described obstacles in the diagnosis, surgery and immediate follow-up of thyroid cancer patients. Unfortunately, patients sometimes find still more barriers in the next part of their journey.
Despite the very encouraging overall statistics for most patients, a segment of the majority with the common (curable) type of thyroid cancer have a more challenging disease -- as they were diagnosed at a later stage and/or have a rare or aggressive sub-variant. Patients over 45 years old at diagnosis and males are amongst those at greater risk. Up to 22% of patients who have the otherwise highly curable form of the disease, fall into a high-risk group(12,13). The survival rate for the latter group drops from an overall 99% to 57%.
A recent study(14) found that patients -- even those initially categorized in the low-risk recurrence group -- have a 4% chance of being diagnosed with a recurrence at five years post-op. The study found that if they were assessed using the thyroglobulin cancer marker test (stimulated Tg blood test), up to 5% tested positive at that point in time and required follow-up testing. This means that all thyroid cancer patients need to remain aware of the possibility of recurrence, even if deemed low risk and with no apparent symptoms.
The significant numbers of patients who may require further assessment for possible recurrence are subject to possible difficulty accessing specialized tests.
One such specialized test is a FDG-PET -- often having utility in cases where there is suspected recurrences of thyroid cancer. A report by Hilner et al(15) indicates that at least 36% of the time (close to average for all cancers), the intended treatment of a thyroid cancer patient is changed as a result of information gleaned in a PET scan. However, despite the obvious value of PET scans for some thyroid cancer patients in a high-risk subgroup, this patient group is affected by unequal distribution of PET scanners across the country; unequal access from province to province in coverage ("indications") for its use; and distinct variation between the number of scanner machines available in a province vs. the actual number of scans performed in that province. For example, Ontario has amongst the highest number of scanning machines, but amongst the lowest ratio of actual scans performed per population. Overall, by population ratio, PET scans are most accessible in New Brunswick and least accessible in British Columbia. Currently, Saskatchewan patients do not have access to PET scans at all within their own province.
How can they find answers if they aren't asking the questions?
One of the most frustrating aspects of thyroid cancer is the relatively low sum of research dollars allocated to it. To make matters worse, the most recent reports indicate that research investment in thyroid cancer actually decreased in 2009 as compared to 2008, even though incidence rates were on a steep upward trend. The 2011 report16 produced by Cancer Research Investment in Canada (CRIC), combined with actual number of patients diagnosed in the same year,(17) indicates that an average of $167 was allocated per newly-diagnosed thyroid cancer patient in 2008. The CRIC's most recent report18 identifies that in 2009 the investment ratio dropped to $111 per newly-diagnosed thyroid cancer patient. Comparatively in 2009, thyroid cancer was allocated 0.1% of research dollars whereas breast cancer received 13.7% of all research dollars ($3,283 per newly-diagnosed breast cancer patient).
You'll be fine?
Despite thyroid cancer patients benefiting from having amongst the highest cure rate of any cancer group, they also have amongst the highest rate of financial bankruptcy(19). Perhaps this can be explained by the often prolonged period of time leading to diagnosis, waiting times for surgery, recovery, treatment, and adjustment to thyroid hormone replacement. Once diagnosed with thyroid cancer, the treatment and follow-up for thyroid cancer is lifelong. Thyroid replacement hormone is not only necessary for the general well-being and health of the patient, but it is also a form of treatment against recurrence; second in importance to the thyroidectomy surgery itself. It is not unusual for patients to require a prolonged series of titrations of their dosage initially, as well at other points in their lifecycle to create the ideal level of hormone. During this balancing process, the patient may feel very unwell.
Additionally, the preparation for and recovery from RAI treatment (if needed) often takes weeks or months, and patients must be isolated for at least one week post-treatment.
As was discussed above, patients also require years of periodic follow-up tests as there is a chance of recurrence.
The combination of all these factors may help explain why thyroid cancer patients have the second highest risk of financial bankruptcy, measured as a conditional probability at five years post diagnosis.
Off the radar
Despite the significant rise in incidence, the high prevalence, the lack of explanation for causes of the disease and/or conflicting theories of causal links20, proportionally little attention is paid to thyroid cancer.
A very simple internet Google search of "breast cancer," for example, leads one to more than 127 million hits, whereas a "thyroid cancer" search will only produce five million listed links (less than .04% as many links). Thyroid cancer is not a disease of high interest in publications. Another telling sign is a simple word count in the recent American Cancer Society publication "Cancer Facts & Figures 2012"(21). The average number of words in each section of description of the six “leading cancers” (which includes: new cases, deaths, signs and symptoms, risk factors, early detection, treatment and survival) is 480 words on average per cancer. In contrast, the word count for thyroid cancer is 288 words.
Thyroid cancer patients in Canada are often not included in data-gathering or reporting, or not proportionally so. Some reports and/or articles about leading cancers are published without a word about thyroid cancer.(22)
One could argue that there is a definite bias in the data gathering and reporting itself. For example, Statistics Canada combines the two decades of ages 20-29 and 30-39 together into one age range period (ages 20-39) for its data reporting, whereas it singles out all the other decades of life for its calculations(23). It does so because cancer is normally a disease of older adults and it is rare for people less than 39 years old to be struck by cancer. The trend is quite the reverse for thyroid cancer and, in fact, the incidence falls into a bell curve pattern with many women being diagnosed in their 30s -- thus, the Stats Canada charts are not reflective of our disease trends.
The lack of attention paid to thyroid cancer is, in effect, a circular problem. In very simple terms – with less exploration of thyroid cancer, fewer resources are assigned to it. With fewer resources assigned, it remains an unknown entity – and we wait longer for significant advancements.
Huffington Post says: "Thyroid Cancer? Sign Me Up" -- as if it's no biggie
Overall, thyroid cancer has a 97% cure rate(24). Thyroid cancer's uniquely overall positive prognostic outlook can paradoxically have a negative effect on patient experience. There seems to be a pervasive attitude that thyroid cancer is in some way a less anxiety-provoking diagnosis or at least it should be. Many patients report being told that they have "the good cancer" or an even more frustrating oxymoronic phrase is used, i.e. that they have a "benign cancer." This attitude, although perhaps well-intended, is not helpful to most patients who feel more reassured with knowledge about the disease rather than positive off-handed comments, often interpreted by patients as flippant and uncaring.
Thyroid cancer patients greatly appreciate knowing that, statistically, thyroid cancer is a very curable and treatable disease. However, thyroid cancer -- even under the most ideal conditions -- in effect, causes a chronic disease state that requires life-long monitoring.
Increasing supportive opportunities to this relatively small population (5,600 new patients in 2012(25)) is crucial as thyroid cancer patients report initial and long-term needs for adequate emotional and informational support. For example, in an international Thyroid Cancer Alliance patients' survey (2010)(26), thyroid cancer patient-respondents reported that the diagnostic stage and anxiety it produced was the most difficult time in their cancer journey. Patients surveyed reported that more information about the disease initially would have improved their cancer journey (77% did not receive professional support; 93% were not offered psychological support; 84% were not given details of a patient support organization; 63% were not given clear written information about the disease and its treatment).
Not only are the initial months worrisome for thyroid cancer patients, but a study from the Netherlands(27) indicates that the effects of the diagnosis and surgery for thyroid cancer have long-lasting emotional consequence. This comprehensive examination using four Quality of Life indices found that thyroid cancer has a significant impact on psychological well-being; worse for this population than for survivors of melanoma or colorectal cancer. The study found that emotional equilibrium was restored on average "after a relatively long duration of cure of approximately 12 to 20 years."
A recent Canadian-based study by Sawka et al28 reflected the increased emotional needs of thyroid cancer patients. The study found that the level of "worry" assessed in a survey of more than 930 thyroid cancer patients (as per an established "Assessment of Survivor Concerns" questionnaire) was statistically significant and even greater than in survivors of several other cancers, including breast cancer. The research found that thyroid cancer survivors' cancer-related worry is most frequently focused on their personal health or health of their children.
Thyroid Cancer Canada(29) is the only organization exclusively offering support and information to thyroid cancer patients in Canada. It does so on a small budget, solely with a volunteer workforce, and with great need for sustainable support. Other organizations available divide their resources amongst numerous forms of cancer, or multiple forms of thyroid disease, or are not Canadian-based.
Certainly there is cause for more research to help ascertain the elements that lead to the development of thyroid cancer, how to prevent it, and how to best treat it. Despite the obvious growing patient population and the needs of thyroid cancer patients, resources in the medical community are not keeping pace. There is a great demand for more expert clinicians, diagnostic tools, researchers, support services, and more informational resources.
There is great need for investment in all aspects of our unique cancer.
For a detailed version of this article, see "Facts & Figures":
- World Health Organization, International Agency for Research on Cancer: http://globocan.iarc.fr/
- Canadian Cancer Society, Canadian Cancer Statistics, 2011
- Canadian Cancer Society, Canadian Cancer Statistics, 2009
- Canadian Cancer Society, Canadian Cancer Statistics, 2011
- TIME Magazine, Health Special, June 2, 2011, "The Screening Dilemma", Kate Pickert: http://www.thyroidcancercanada.org/userfiles/files/TIME_Magazine_The%20Screening%20Dilemma.pdf
- Davies L, Welch HG. Increasing incidence of thyroid cancer in the United States, 1973-2002. JAMA 2006; 295:2164-7; Kent WD, Hall SF, Isotalo PA, et al. Increased incidence of differentiated thyroid carcinoma and detection of subclinical disease. CMAJ 2007; 177:1357-61
- Increasing incidence of differentiated thyroid cancer in the United States, 1988-2005, Chen AY, Jemal A, Ward EM; The utilization of sensitive diagnostic procedures does not completely explain the observed increased incidence in papillary thyroid cancer over three decades. Enewold L, Zhu K, Ron E, Marrogi AJ, Stojadinovic A, Peoples GE, Devesa SS. 2009:
- Thyroid cancer incidence patterns in the United States by histologic type, 1992-2006, Aschebrook-Kilfoy B, Ward MH, Sabra MM, Devesa SS.8 http://www.waittimes.net
- Volume-Based Trends in Thyroid Surgery, Christine G. Gourin, MD; Ralph P. Tufano, MD; Arlene A. Forastiere, MD; Wayne M. Koch, MD; Timothy M. Pawlik, MD, MPH; Robert E. Bristow, MD, December 2010: http://archotol.jamanetwork.com/article.aspx?articleid=497091
- Canada Sees Mixed Trends in Thyroid Cancer, by Fran Lowry, September 21, 2009 (re: study by Stephen Hall, MD): http://www.thyroidcancercanada.org/userfiles/files/Canada%20Sees%20Mixed%20Trends%20in%20Thyroid%20Cancer%20-%20Cancer%20Network.pdf
- Regional Differences in Opinions on Adjuvant Radioactive Iodine Treatment of Thyroid Carcinoma within Canada and the United States, Anna M. Sawka et al, THYROID, Vol 12 No: 12, 2007: http://www.thyroidcancercanada.org/userfiles/files/RAI_Regional_Sawka.pdf
- Thyroid Cancer: Extent of Thyroidectomy, Ashok R. Shaha, May 2000, Cancer Control Journal, http://www.thyroidcancercanada.org/userfiles/files/Thyroid%20Cancer_%20Extent%20of%20Thyroidectomy.pdf
- Current Approaches to Primary Therapy for Papillary and Follicular Thyroid Cancer, Ernest L. Mazzaferri and Richard T. Kloos, The Journal of Clinical Endocrinology & Metabolism Vol. 86, No. 4 1447-1463, 2001
- Hillner BE, Siegel BA, Shields AF et al. (2008b). Relationship between cancer type and impact of PET and PET/CT on intended management: findings of the national oncologic PET registry, J Clin Oncol 26(13):2156-2161
- Canada Research Investment in Canada 2008 (published 2011)
- Canadian Cancer Society, Canadian Cancer Statistics, 2008
- Canada Research Investment in Canada 2009 (published 2012)
- Cancer diagnosis as a risk factor for personal bankruptcy. S. D. Ramsey, C. R. Fedorenko, K.S. Snell, A. C. Kirchhoff, W. Hollingworth, D. K. Blough; Fred Hutchinson Cancer Research Center, Seattle, WA; University of Bristol, Bristol, United Kingdom; University of Washington, Seattle, WA J Clin Oncol 29: 2011 (suppl; abstr 6007) http://www.asco.org/ASCOv2/Meetings/Abstracts?&vmview=abst_detail_view&confID=102&abstractID=82633
- Peterson E, De P, Nuttall R, 2012 BMI, Diet and Female Reproductive Factors as Risks for Thyroid Cancer: A Systematic Review. PLoS ONE 7(1): e29177. doi:10.1371/journal.pone.0029177
- American Cancer Society. Cancer Facts & Figures 2012. Atlanta: American Cancer Society; 2012
- Age-specific, Five-year proportions for all cancers combined, by Sex, Canada, January 1, 2005, Table 3, Statistics Canada, http://www.statcan.gc.ca/pub/82-003-x/2009001/article/10800/tbl/t3-eng.htm
- Statistics Canada, http://www.statcan.gc.ca/pub/82-226-x/2012001/t117-eng.htm
- Canadian Cancer Society, Canadian Cancer Statistics, 2012
- Thyroid Cancer Alliance, International Thyroid Cancer Survey, http://thyroid-cancer-alliance.org/tca-wp/news/survey-2010/
- Quality of Life in Cured Patients with Differentiated Thyroid Carcinoma, Hendrieke C. Hoftijzer, Karen A. Heemstra, Eleonora P. M. Corssmit, Agatha A. van der Klaauw, Johannes A. Romijn, and Johannes W. A. Smit, J Clin Endocrinol Metab. January 2008, 93(1):200–203 http://www.thyroidcancercanada.org/userfiles/files/Quality_of_Life_Study_2007.pdf
- Abstract, poster presentation: http://www.thyroidcancercanada.org/userfiles/files/Sawka_Study_support_&_worry_2012_abstracts.pdf
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