Net survival and the probability of cancer death from rare cancers

Cancers for which fewer than 6 people per 100,000 population are diagnosed every year are designated as “rare cancers”. Rare cancers are relatively under-researched, and little information is available on survival, even though, collectively, they account for almost a quarter of all cancers diagnosed in adults in Europe.

We have estimated net survival and the probability of cancer death (also known as the crude probability of death) for patients in England who were diagnosed aged 15-89 years with one of 13 rare cancers between 1999 and 2013 who had follow-up time between 2009 and 2013. We also provide recent survival estimates for the 25 most common cancers for patients aged up to and including 99 years at diagnosis.

The rare cancers studied were those of the tongue, oral cavity, salivary glands, oropharynx, hypopharynx, small bowel, anus, gallbladder, nasal sinuses, bones, vagina, penis and eye.

Rules for analysis

We specified rules restricting the analyses to cancers and periods of follow-up for which sufficient data were available to make robust estimates of survival. We only estimated survival up to 10 years of follow-up because estimates after this point are frequently unstable due to small numbers of patients left at risk. For rare cancers we restricted the analysis to patients aged 15-89 at diagnosis and did not estimate survival beyond 5 years of follow-up for patients aged 70-89, because survival estimates are unstable when there are few patients at risk initially and when the number at risk drops sharply over time.

Survival at a certain time since diagnosis, and the corresponding probability of death, is only reported if at least 10 patients were alive at that time; and if there were at least 5 events in either the period before or the period after this time; and if there was at least one event in the two years before this time. As a result if the patient numbers are too small for survival estimates to be robust then the estimates are not reported.

Selected results

Of the 13 rare cancers studied, survival at one year after diagnosis was lowest among patients with gallbladder, hypopharynx and small bowel cancer at 47% (95%CI 46-48%), 58% (56-61%) and 66% (65-67%) respectively. Highest survival was among those with eye cancer (86% of which are melanomas), penile and salivary gland cancers at 94% (93-96%), 88% (86-90%) and 84% (83-86%) respectively.

The three rare cancers whose patients had the lowest one-year survival also had the lowest five-year survival: gallbladder 20% (19-21%), hypopharynx 27% (25-30%) and small bowel 44% (43-46%). Five-year survival was 68% (65-71%) for eye cancer, 72% (70-76%) for penile cancer and 64% (62-67%) for salivary gland cancer.

Click on the links below for full results:

Muller P, Belot A, Morris M, Rachet B (2016)

Work funded by through the CSG Cancer Policy Programme.

Further information on net survival can be found in:

Pohar Perme M, Stare J, Estève J (2012) On estimation in relative survival. Biometrics 68: 113-120