The prevalence of lymphedema in Canada: An update Accurate determinations of prevalence remain a challenge
By David Keast, Anna Towers, Marie-Ève Letellier and Alisha Damji
Abstract: It is vitally important to know the prevalence and impact of a condition to justify the allocation of health care resources. Chronic edema/ lymphedema continues to be poorly recognized and poorly treated. Even within the lymphedema community, some basic questions still need to be answered. How do we define lymphedema? What diagnostic methods should be used? What volume differences? We have no accepted international guidance on this. In estimating prevalence, do we only include stages 2 and 3, ignoring those in earlier stages who might only have limb swelling and/ or feel heaviness at the end of the day? For the purposes of the current exercise, we have only considered those with established chronic edema/ lymphedema; however, those with early signs also need preventive advice and treatment.
Truegeneral population prevalence studies are difficult to conduct, but there is a significant body of knowledge internationally involving specific populations through the Lymphoedema Impact and Prevalence International (LIMPRINT) group of studies. These studies use a standardized case-finding protocol in a Core Tool. The currently accepted definition of chronic edema/lymphedema is swelling present for more than three months, minimally responsive to limb elevation and/ or diuretics2. It is accompanied by low-level chronic inflammation that leads to further tissue damage. Diagnosis is easier once skin and subcutaneous fibrotic changes are already present, although the person now already has more advanced and often irreversible stages
of the condition. If venous disease is involved, clinicians often label these patients as having ‘stasis dermatitis’ rather than chronic edema/ lymphedema.
In the Spring 2017 issue of Pathways Keast and Towers presented their estimate of the prevalence of lymphedema in Canada, with justifying discussions, using the evidence available at the time. The known risk factors for lymphedema were examined and prevalence was estimated according to risk category. The authors indicated that, in contrast to common perception, the leading cause of lymphedema in Canada is not cancer treatment but marked obesity, with or without venous disease. The obesity rate continues to increase in developed countries. It is therefore
David Keast MD is the Medical Director of the Outpatient Chronic Wound Management Clinic at the Parkwood Institute (London) and Clinical Adjunct Professor of Family Medicine, Schulich School of Medicine and Dentistry and Associate Scientist in the Parkwood Research Institute.
Anna Towers MD is a palliative care physician and Director of the Lymphedema Program and the Support Centre of the Quebec Breast Cancer Foundation at the MUHC, McGill University Health Centre, Montreal. In 2021 this Program was recognized as a LE&RN Comprehensive Network of Excellence.
Marie- Ève Letellier PhD CDT Kinesiology has been working in close collaboration with Dr. Anna Towers for almost 20 years and is currently combining research and clinical work at the MUHC Lymphedema Clinic (Montreal).
Alisha Damji joined the CLF during the summer of 2024 as a co-op student from Wilfrid Laurier University’s Honors Health Sciences program. She contributed to marketing, outreach, administrative support and special projects.
no surprise that obesity continues to be the predominant causative factor. In this article we present updated figures, tending to err on the side of underestimating the condition in our calculations. As stated in that 2017 article, it is very important to note that these continue to be preliminary discussions. We need more research in order to better define the prevalence of chronic edema/lymphedema in the population.
Cancer-related lymphedema
There are challenges in estimating the incidence of cancer-related lymphedema. The primary challenge is the lack of international agreement on what degree of volume excess is considered lymphedema, and/or what imaging techniques should be used.
We know that the cancer rate in Canada is increasing because of the aging population4 Therefore, though patients are being treated more conservatively (e.g. with sentinel node biopsies rather than with more extensive node dissections, and with more targeted radiotherapy rather than the wider fields used in the past) the prevalence rate of cancer-related lymphedema is estimated to have remained stable compared to 10-15 years ago.
Statistics Canada produces a yearly update on the incidence of various types of cancer, along with an estimate of the number of cancer survivors4. With that in hand, along with an increasing number of research reports on the incidence of cancer-related lymphedema, we can update the figures in our previously published Pathways article (2017). Recent reports help us better define the incidence of lymphedema related to various cancers, in particular breast and gynecological cancers, and melanoma.
In 2023, mandated by the Lymphology Association of North America (LANA) and the American Cancer Society, clinical researchers participated in a North American initiative to update lymphedema clinical guidelines. As part of this initiative8, participants reviewed studies published between 2015 and 2023 and reported variations of incidence for various cancers. Based on this work, and what was previously published by Cormier et al (2010) and Shaitelman et al (2015), we have an updated estimate of lymphedema incidence for the following cancers: breast 17%, gynecological 25%, melanoma 9%, genitourinary 11%, sarcoma 30%, head and neck 60%. If we take the yearly incidence of these cancers in Canada, multiplied by predicted survival and by lymphedema incidence, we arrive at a gross estimate of 350,000 Canadians affected by cancer-related lymphedema. In many studies lymphedema incidence might be under-estimated, based on the methods used to diagnose the condition. Treatment for several other cancers can commonly lead to lymphedema, and for these we do not have much data beyond the expert opinion of lymphedema specialists. These include colorectal, lung, kidney, and squamous cell skin cancers.
Obesity-related lymphedema
The rising prevalence of Class III obesity remains the leading cause of chronic edema/ lymphedema in Canada. Until recently, we have been relying primarily on expert opinion regarding the risk of developing lower limb lymphedema based on BMI. Large-scale prevalence studies on the general population do not exist. Much of the data we have comes from those patients who already have established chronic edema, such as in the LIMPRINT studies, and the observation that a high proportion of patients attending lymphedema clinics are obese (Shallwani et al 2019, Keast 2022). Greene et al (2021) searched their clinical database for patients with a diagnosis of obesity-induced lymphedema, based on lymphoscintigraphy studies, comparing them with patients who had obesity but no lymphedema. The risk of having lower extremity lymphedema was predicted by BMI as follows: BMI < 40 (0%), 40-49 (17%), 50-59 (63%), 60-69 (86%), 70-79 (91%), ≥80 (100%).
In a recently published paper from the LIMPRINT study, based on a database of 7397 patients, the authors report that more than half
of the patients with chronic leg oedema/lymphoedema are affected by obesity, and the severity of oedema increases with each weight category (Burian et al, 2024). The most advanced stage of lymphoedema (ISL stage III), with fibrotic tissue and skin changes, affected 14% of patients with normal weight, 18% with class I-II obesity, and 39% with class III obesity.
As of October 1, 2024, the total Canadian population reached 41.7 million, according to the Real-Time Model for Stats Canada. Of the total, 8.4 million were children under age 18, giving an adult population of 33.3 million. Stats Canada data for adults showed that class 2 obesity rates (BMI – 35-39) increased from 2.3% in 1978-79 to 5.1% in 2004. The class 3 rates (BMI >40) increased from 0.9% to 2.7% over the same time period. By 2018, the rate of class 3 obesity had increased to 4%. At the same rate of increase the class 2 obesity rate is predicted to be 7.5% in 2018. Based on the study by Greene et al (2021) the prevalence of lymphedema in persons with class 3 obesity is 33.4%. Based on the LIMPRINT study that included persons who had class 2 obesity, we can estimate that the prevalence of lymphedema in those with class 2 obesity is 10%. By using the adult population data in combination with relative prevalence data we can conservatively estimate the number of Canadians with class 3 obesity and lymphedema is 440,000 and the number with class 2 obesity and lymphedema is 250,000. This results in a total of 690,000 persons in Canada with obesity and lymphedema.
Chronic venous insufficiency (CVI) Between 10 and 35% of the United States population, depending on age, has CVI. (Brajesh 2015) At any given time, 1% of adult populations in developed countries have an active venous leg ulcer, rising to 4% in persons over 65. (Woo 2015) In a study of 326 persons
with lymphedema, on average they had 7.3 coexisting risk factors for chronic swelling; 75% had a history of venous disease and 45% had class 3 obesity. (Wang 2016) Although venous disease is a common cause or contributor to chronic edema, we have not attempted a prevalence estimate for this category in order to avoid double-counting. We can only suggest that those with venous insufficiency and no contraindication to compression should consider using medicalgrade compression stockings for the prevention of chronic edema and wounds, especially if they also have obesity.
Decreased mobility
Wheelchair-bound patients such as spinal cord injured, older persons post-stroke, and patients who are housebound and dependent on community services – all have a high rate of chronic edema. Those with other conditions such as multiple sclerosis, cerebral palsy, muscular dystrophy or other neuromuscular disorders may have significant gait abnormalities leading to calf muscle pump failure and increased risk of chronic edema. Current Canadian estimates indicate 90,000 persons living with multiple sclerosis, 85,500
persons post spinal cord injury, and nearly 900,000 post-stroke, two-thirds of whom are estimated to have mobility disorders. Conservatively 750,000 Canadians are living with a significant mobility disorder. If we estimate that 20% have chronic edema, the number due to mobility disorders is 150,000. Many also have obesity, but some do not. If we discount this number by one quarter to avoid double-counting again, we are underestimating the prevalence of chronic edema in Canada by including a conservative figure of 113,000 for all those patients with chronic edema related to immobility who have no other risk factors.
Other surgeries
There are many types of surgery other than for cancer that can lead to chronic edema.
In 2021-22 more than 117,000 hip and knee replacements and 15,000 coronary artery bypass graft surgeries were performed in Canada. If we assume conservatively that survival will be only five years, and that half have obesity and therefore eliminated from the calculation to avoid double-counting, and if we further assume a 25% chronic edema rate for the remainder, we arrive at a figure
There is little data on the prevalence of primary lymphedema that is first diagnosed in adulthood, although we do see such cases, and not infrequently, in lymphedema practices.
of 83,000 non-obese Canadians with chronic edema following these surgeries. This does not count persons who have had multiple abdominal surgeries, fractures, or other trauma, who will also have chronic edema.
Primary lymphedema
Compared to other causes of chronic edema, primary lymphedema is considered relatively rare. We also know that this condition can manifest at any time of life, not only in childhood. There is little data on the prevalence of primary lymphedema that is first diagnosed in adulthood, although we do see such cases, and not infrequently, in lymphedema practices.
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Prevalence rates in the literature vary greatly and tend to focus on primary lymphedema in children. The incidence already manifest at birth is quoted as 1 in 6000 births (Compendium of Vascular Anomalies, 2021). Prevalence estimates are around 1:10,000 of the population (Schwartz, 2023). However, some who manifest primary lymphedema in childhood may not be diagnosed until adulthood. Vignes and Queré (Orphanet, 2018) seem to have taken this into consideration in using the prevalence estimate of 1:2000 from the European Registry. Those who first develop the condition as adults are also likely not diagnosed or are misdiagnosed. Given this reality, we have chosen to use a figure which we believe is still conservative at 1:2000 of the general population which would place the prevalence at 21,000 for Canada. With the increasing obesity rate, patients with primary lymphedema may develop multifactorial chronic edema, adding obesity, cancer treatments, chronic venous insufficiency and immobility to their primary etiology.
Conclusion
Chronic edema/lymphedema are prevalent and underdiagnosed conditions in Canada. By our conservative estimate, even excluding those with venous disease and no other risk factors, over 1.25 million persons in Canada have lymphedema (Figure 1). However, the prevalence estimates outlined here are meant to represent ranges rather than absolute numbers. We have little or no Medicare diagnostic data to help us, as these conditions are underdiagnosed and are not reported as such. We need more research within specific populations in order to be able to more accurately estimate prevalence in the future. According to LE&RN, over 10 million persons in the USA have lymphedema. Based on the relative populations of the two countries, our figures for Canada correspond to that. We need more research on the population prevalence chronic edema related to obesity and venous disorders. To try to prevent
lymphedema and its complications (functional impact, wounds, bacterial cellulitis, risk of sepsis) clinicians might consider whether patients with class 3 obesity should be prescribed properly fitted, medical grade compression stockings -- especially if these patients also have chronic venous insufficiency. The population needs information regarding the importance of exercise and weight control. Resources need to be directed towards the prevention and treatment of obesity. LP
References can be found at https://canadalymph.ca/ pathways-references
Acknowledgement:
Thanks to Bonnie Baker, Executive Director of the Canadian Lymphedema Framework, for her bibliographic and editorial work on this project.
How to cite: Keast D, Towers A, Letellier ME, Damji A. The prevalence of lymphedema in Canada: an update. Accurate determinations of prevalence remain a challenge. Pathways. 2025;14(1): 5–8. DOI: https://doi.org/10.70472/CDPU5571
