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Ontario Cancer Facts

Rare cancers have a high impact on people

Nov 2021

Highlights

 

  • Rare cancers in Ontario have a high impact because people with these cancers often face longer delays in diagnosis, have fewer treatment options and, as a result, have lower survival than people with more common cancers.
  • Rare cancers tend to affect more people ages 15 to 39 than common cancers do.
  • More research is needed on rare cancers in Ontario and in Canada.

Due to their unique challenges, which often lead to poorer outcomes, rare cancers have a high impact on people in Ontario. From 2012 to 2016, for all ages combined, 5-year relative survival was significantly lower for rare cancers (56.6%) than for common cancers (68.8%) (data not shown).

Many factors can contribute to poorer outcomes for rare cancers:

  • Little understanding about how to effectively prevent and treat many rare cancers because research about them is limited, and the low number of people with these cancers makes clinical trials difficult to conduct
  • Limited information about risk factors for many rare cancers, so prevention programs and population-based screening tests are lacking
  • Lack of familiarity with rare cancers by primary care physicians, which can lead to delays in diagnosis
  • Few specialists treat rare cancers, which may result in treatment delays
  • Limited treatment options for some rare cancers can mean poorer outcomes
  • Unavailable or limited information on rare cancers and social support services focused on rare cancers contributes to feelings of alienation, confusion and stress

A cancer is considered rare if it is diagnosed at a rate of fewer than 6 cases per 100,000 people each year. This is compared with the 4 most common cancers, which are diagnosed at rates ranging from 57 (colorectal) to 145 (breast) cases per 100,000. The definition for rare cancers used here was created by the RARECARE consortium from the European Union, which identified 198 rare types of cancer. Rare cancers include cancers such as testicular and esophageal cancers, sarcomas and glioblastomas, as well as lesser-known cancers, such as squamous cell carcinoma of the nasal cavity and sinuses.

From 2012 to 2016, rare cancers collectively accounted for a fifth of all new cancer cases diagnosed (75,630 cases) and nearly a quarter of all cancer deaths (31,800 deaths). This is in contrast to the 4 most common cancers (breast, lung, colorectal and prostate), which made up nearly half of all cancers diagnosed in Ontario during the same period (184,166). Other common cancers, such as melanoma and bladder, made up the remaining one-third of cancers diagnosed in Ontario (140,825) (data not shown).

Younger people are disproportionately affected by rare cancers. This may be because many rare cancers are likely caused in part by genes that make people susceptible to developing certain rare tumours earlier in life versus common cancers, which more often arise because of aging. From 2012 to 2016, the relative proportion of rare cancers (11.4%) was almost 3 times greater in people ages 15 to 39 than the relative proportion of common cancers (3.9%) (see figure). In this age group, rare cancers also represented nearly double the proportion of cancer deaths (2.0%) compared with common cancers (1.1%) (data not shown).

Analysis by: Surveillance, Ontario Health (Cancer Care Ontario)

Source: Ontario Cancer Registry (December 2018), Ontario Health (Cancer Care Ontario)

Notes:
Common cancers include any cancer with an annual incidence rate of at least 6 per 100,000.
Rare cancers include all other cancers with an annual incidence rate of less than 6 per 100,000.
The definition of rare cancers used in this analysis was created by the RARECARE consortium from the European Union. The RARECARE examination of rare cancers is the most comprehensive analysis to date on the incidence of rare cancers, which includes not only topographical categories (anatomical), but also histological categories.
Cancers diagnosed in children under age 15 are excluded from this analysis because all types of cancer in children meet the definition of a rare cancer.

Figure. Proportion of new cases due to rare versus common cancers by age group, Ontario, 2012 to 2016
Age group Common Cancers Rare Cancers
15 - 39 years 3.9% 11.4%
40 - 59 years 25.3% 23.3%
60 - 79 years 52.2% 44.4%
80 years or older 18.6% 20.9%

Analysis by: Surveillance, Ontario Health (Cancer Care Ontario)

Source: Ontario Cancer Registry (December 2018), Ontario Health (Cancer Care Ontario)

Notes:
Common cancers include any cancer with an annual incidence rate of at least 6 per 100,000.
Rare cancers include all other cancers with an annual incidence rate of less than 6 per 100,000.
The definition of rare cancers used in this analysis was created by the RARECARE consortium from the European Union. The RARECARE examination of rare cancers is the most comprehensive analysis to date on the incidence of rare cancers, which includes not only topographical categories (anatomical), but also histological categories.
Cancers diagnosed in children under age 15 are excluded from this analysis because all types of cancer in children meet the definition of a rare cancer.

More information is needed on rare cancers in Ontario and in Canada because they are a considerable public health issue. To help address this issue, our Ontario Cancer Statistics 2020 report spotlighted rare cancers as a special topic.

We also are working with our partners in the health system to:

  • Inform the implementation of prevention policies and programs to reduce exposure to risk factors associated with common and rare cancers (e.g., school-based human papillomavirus vaccination program to prevent cervical cancer as well as certain head and neck cancers)
  • Publish evidence-based clinical guidelines and pathway maps for the management of certain rare cancers
  • Develop provincial guidelines and specialized services to ensure that people in Ontario, including those with rare cancers, have access to appropriate care
  • Integrate and coordinate clinical management of certain rare cancers provincially
  • Routinely monitor outcomes of people with cancer and the delivery of health services to ensure that high-quality cancer care is being provided

More information

References

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  2. Greenlee RT, Goodman MT, Lynch CF, Platz CE, Havener LA, Howe HL. The occurrence of rare cancers in U.S. adults, 1995-2004. Public Health Rep. 2010;125(1):28-43.
  3. Blay JY, Coindre JM, Ducimetière F, Ray-Coquard I. The value of research collaborations and consortia in rare cancers. Lancet Oncol. 2016;17(2):e62-e69.
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  6. RarecareNet. Information Network on Rare Cancers. Cancer List. Available from: http://rarecarenet.istitutotumori.mi.it/rarecarenet/index.php/cancerlist (Accessed Aug 25, 2021).
  7. Gatta G, van der Zwan JM, Siesling S, Otter R, Tavilla A, Mallone S, et al. (2010). Technical report with basic indicators for rare cancers and health care related macro indicators. (Grant agreement no. 2006113, Work package 5, deliverable no. 13). Available at: https://research.utwente.nl/en/publications/technical-report-with-basic-indicators-for-rare-cancers-and-healt (Accessed Aug 25, 2021).
  8. Boyd N, Dancey JE, Gilks CB, Huntsman DG. Rare cancers: a sea of opportunity. Lancet Oncol 2016; 17: e52–61.