© 2007 European Society for Medical Oncology
epidemiology |
Prognosis for long-term survivors of cancer
1 Eindhoven Cancer Registry, Comprehensive Cancer Centre South, AE Eindhoven
2 MMC Academy, Máxima Medical Centre, Veldhoven
3 Department of Public Health, Erasmus MC—University Medical Centre Rotterdam, Rotterdam, The Netherlands
4 Division of Clinical Epidemiology and Aging Research, German Cancer Research Centre, Heidelberg, Germany
* Correspondence to: M. L. G. Janssen-Heijnen, Eindhoven Cancer Registry, PO Box 231, 5600 AE Eindhoven, The Netherlands. Tel: +31 40 2971616; Fax: +31 40 2971610; E-mail: research{at}ikz.nl
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Abstract |
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 Top Abstract introductionpatients and methodsresultsdiscussionconclusionAcknowledgementsReferences |
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Background: Many cancer patients who have already survived some time want to know about their prognosis, given the pre-condition that they are still alive. We described and interpreted population-based conditional 5-year relative survival rates.
Patients and methods: The long-standing Eindhoven Cancer Registry collects data on all patients diagnosed with cancer in the southern part of the Netherlands. Patients aged 25–74 years, diagnosed between 1960 and 2004, were included. Conditional 5-year relative survival was computed for every additional year survived (follow-up period 1980–2004).
Results: For patients with colorectal cancer, cutaneous melanoma or stage I breast cancer, conditional 5-year relative survival was >95% after having survived 3–15 years. However, for stomach, lung, stage II or III breast, prostate cancer or Hodgkin lymphoma, conditional 5-year relative survival did not exceed 75–94%. Initial differences in survival at diagnosis between age, gender and stage groups largely disappeared after having survived for 5–10 years.
Conclusion: Prognosis for patients with cancer generally improved with each year survived. Patients with colorectal cancer, cutaneous melanoma or stage I breast cancer hardly exhibit any excess mortality after 3–15 years, whereas for patients with other tumours survival remained poorer than for the general population. Insight into conditional survival is especially useful for (ex)patients, who may use this information to plan their remaining life.
Key words: cancer, conditional survival, long-term prognosis, period survival, population-based
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introduction |
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TopAbstractintroductionpatients and methodsresultsdiscussionconclusionAcknowledgementsReferences |
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Patients who have survived for a certain amount of time after cancer diagnosis often want to know about their prognosis at that time. Standard survival curves at diagnosis of cancer are too negative, because these are also based on patients who die within the first years. Conditional survival analysis is a method for estimating the survival rate, given the pre-condition of having already survived a certain length of time [1]. For example, 5-year relative survival at diagnosis of stomach cancer is 20%. After 5 years, 80% of the patients have died from stomach cancer. Patients who are still alive at 5 years belong to a group of survivors with at that moment a much better prognosis than at diagnosis. Conditional survival rates can provide patients and treating physicians with more relevant information for personal health-related future planning [2]. For estimating conditional survival rates [1, 3-8], a long-term and complete follow-up is needed. Some previous studies have presented conditional survival rates, most of them with data from the Surveillance, Epidemiology and End Results (SEER) in the United States. Only one of them [8], pertaining to patients diagnosed in the 1970s, has presented conditional survival rates for those still alive >5 years after diagnosis and one study has estimated the conditional probability of cure up to 15 years after diagnosis of cutaneous melanoma [9].
In this article we determined conditional 5-year relative survival rates for contemporary cancer patients. Specifically we were interested in the time interval between diagnosis and conditional relative survival becoming close to 100%, whether patients with specific cancers had a deteriorating long-term conditional survival, and in the long term influence of prognostic factors such as age and tumour stage. We considered conditional 5-year relative survival for every additional year survived up to 20 years, using population-based data from the long-standing Eindhoven Cancer Registry.
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patients and methods |
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TopAbstractintroductionpatients and methodsresultsdiscussionconclusionAcknowledgementsReferences |
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The Eindhoven Cancer Registry has collected data on all patients with newly diagnosed cancer in the southern part of the Netherlands since 1955 (completeness >95% [10]). The registry now serves a population of 2.3 million inhabitants. The area offers good access to specialized medical care in 10 general hospitals and two large radiotherapy institutes. Data on vital status, available up to 1 January 2006, were obtained from the hospital records and the death register of the Central Bureau for Genealogy, which registers all deceased in the Netherlands via the municipal civil registries. Patients who had moved and died outside the Netherlands may have been wrongly considered as being alive, but the estimated proportion of these patients was <0.3%.
In this article we present only the results for the major cancer types: cancer of the digestive tract (stomach, colon, rectum), non-small cell lung cancer (NSCLC), breast cancer, cutaneous melanoma and prostate cancer. Furthermore, to illustrate the effect of side-effects of treatment, late recurrences or progression, we also included patients with Hodgkin lymphomas. Conditional survival curves for other tumour sites can be found on our website (ikz.figures.ikcnet.nl). Patients aged 25–74 years and diagnosed between 1960 and 2004 were selected. We excluded patients with T4 or metastasized disease (M+) at diagnosis and those diagnosed at autopsy.
We calculated 5-year relative survival rates with period analysis [11-13]. Period analysis provides the most up-to-date survival rates, because all observations included in the analyses are left-truncated at the beginning of the period of interest in addition to being right-censored at its end. We estimated relative survival rates using period analysis for the follow-up period 1980–2004. Relative survival is an estimation of disease-specific survival. It is calculated as the absolute survival rate among cancer patients divided by the expected survival rate of a comparable group from the general population with the same sex and age structure in the same period (derived from Statistics Netherlands). For each tumour type, 5-year relative survival was computed for every additional year survived up to 20 years, conditional on being alive at that moment. Since patients who have already survived for some years are older than at diagnosis, conditional relative survival rates were also adjusted for survival in the general population with the same age structure as patients at that time. We computed these rates for two age groups (25–49 years and 50–74 years). For patients with cutaneous melanoma or Hodgkin lymphoma, conditional relative survival was significantly different for males and females and therefore we present survival for these tumour groups by gender. For patients with colon or breast cancer, we also computed conditional survival rates for each stage group, according to the Tumour-Node-Metastasis (TNM) system of the Union Internationale Contre le Cancer. Since stage of disease has been reliably recorded only since 1980, survival analyses for the stage groups were limited to patients diagnosed between 1980 and 2004. We presented only conditional relative survival rates with a standard error of 
5% of the survival proportion. We also computed relative survival rates at diagnosis (period of diagnosis 1980–2004). Relative survival rates were calculated with the SAS computer package (SAS Institute Inc., Cary, NC, USA, 1999), using a publicly available macro for period analysis [14].
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results |
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TopAbstractintroductionpatients and methodsresultsdiscussionconclusionAcknowledgementsReferences |
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Table 1 shows the numbers of patients available for conditional period survival analysis after 5, 10, 15 and 20 years for each tumour type, the number of years after diagnosis when there was hardly any excess mortality (conditional 5-year relative survival is consistently >95%) and the number of years after diagnosis when the upper end of the 95% confidence interval includes 95% conditional 5-year relative survival.
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Figure 1 shows the relative survival curve at diagnosis for each tumour type, as well as the conditional 5-year relative survival rate for each additional year survived.
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Five-year relative survival at diagnosis for patients with stomach cancer (M+ excluded) was rather poor (41% for those aged 25–49 years and 31% for those aged 50–74 years). However, the chance of surviving another 5 years increased steeply to 89% and 83%, respectively, for those still alive after 5 years (Figure 1a).
For patients with colon or rectal cancer, conditional 5-year relative survival also increased with time since diagnosis, although much less steeply. For those aged 25–49 years, conditional 5-year relative survival was > 95% after 12 and 9 years for colon and rectal cancer, respectively (Figure 1b and d). The same pattern was seen for those aged 50–74 years, although conditional relative survival for the elderly with colon cancer slightly decreased again after 10 years. Although survival at diagnosis was clearly different for each stage group, this difference (almost) disappeared after survival for 6 years (Figure 1c).
For patients with NSCLC, conditional 5-year relative survival never exceeded 91% for those aged 25–49 years and 77% for those aged 50–74 years (Figure 1e).
Five-year relative survival at diagnosis was 
70–80% for male patients with cutaneous melanoma in contrast to 89–93% for female patients. Conditional survival was very similar for the two age groups, and after 3–7 years, conditional 5-year relative survival was almost equal to survival in the general population with the same age structure (Figure 1f and g).
For patients with breast cancer, 5-year relative survival at diagnosis was 84% for both age groups (Figure 1h). Conditional 5-year relative survival became 90–94% between 8 and 20 years after diagnosis. For patients with stage I breast cancer, 5-year conditional survival was >95% at 15 years after diagnosis (Figure 1j). For patients with stage II or III disease 5-year conditional survival did not exceed 88% (18–20 years after diagnosis).
For patients with prostate cancer conditional 5-year relative survival decreased from 89% at diagnosis to 81% 6 years after diagnosis, whereafter it increased again to 91% after 11 years (Figure 1k). This pattern was found for tumours of both stage I/II and stage III (Figure 1l).
Five-year relative survival with Hodgkin lymphoma aged 25–49 years was 84% for male patients and 94% for female patients at diagnosis. For male patients conditional survival improved only slightly with each additional year survived, to 96% at 10 years after diagnosis, but thereafter decreased again slightly (Figure 1m). For female patients conditional survival remained more or less stable over time. There were not enough patients to reliably estimate conditional survival rates for the age group 50–74 years.
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discussion |
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TopAbstractintroductionpatients and methodsresultsdiscussionconclusionAcknowledgementsReferences |
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Patients have hardly any excess mortality when conditional 5-year relative survival exceeds 95%. Survival for this group of patients is then similar to the general population with the same age structure. This was found for patients with colorectal cancer, cutaneous melanoma or stage I breast cancer. However, for other tumours (stomach cancer, NSCLC, stage II or III breast cancer, prostate cancer or Hodgkin lymphomas), conditional 5-year relative survival did not exceed 75–94%. This means that, even when alive at 10–20 years after diagnosis, patients with these tumours still have a poorer survival compared with the general population with the same age structure [15-17]. Potential explanations for the poorer survival compared with the general population include late recurrences, secondary tumours, or a higher death rate due to co-morbidity associated with the risk factors for cancer (e.g. chronic obstructive pulmonary disease and cardiovascular diseases, which are related to smoking in patients with lung cancer).
For some tumour types (such as Hodgkin lymphomas or breast cancer), conditional 5-year relative survival decreased again slightly for patients who had already survived for some time. This could be explained partly by recurrence or progression even after long follow-up [1, 15]. Unfortunately we do not have these data available in our population-based cancer registry. Conditional survival can also decrease after some time because of late side-effects of treatment, such as pulmonary or cardiac conditions or second tumours (e.g. after Hodgkin lymphoma or breast cancer) [18-21]. For prostate cancer, conditional 5-year relative survival decreased up to 6 years after diagnosis, before increasing. The reason for this phenomenon is not clear. An increase in mortality after some time might be expected in the case of a ‘wait and see’ policy or hormonal treatment. In patients up to 70 years this was the case in 30–35% of those with a T1 tumour and in 20–25% of those with a T2 tumour. However, we also found a decrease in conditional survival in the first years after diagnosis for patients with a stage III tumour.
For most tumour types 5-year relative survival at diagnosis was somewhat more favourable for younger compared with older patients [22]. Previous studies have shown that age still influenced conditional survival up to 5 years after diagnosis [1, 4, 5]. In our study we also found a prognostic influence of age on conditional survival in the first years after diagnosis, but this influence largely disappeared after survival for 5–10 years for most tumour types, except for NSCLC.
Five-year relative survival at diagnosis was also clearly different for the stage groups. Previous studies among patients with colon cancer, breast cancer or lung cancer (SEER database) still alive up to 5 years after diagnosis (up to 2 years for lung cancer), have shown that the difference in survival at diagnosis between stage groups decreased with time since diagnosis. Stage, however, remained an important prognostic factor, even for conditional survival after 2–5 years [3, 5, 6]. In studies with a longer follow-up among patients with colon cancer (conditional survival rates up to 20 years after diagnosis), lung cancer (up to 5 years after diagnosis), cutaneous melanoma (up to 15 years after diagnosis) or breast cancer (up to 5 years after diagnosis), the difference between the stage groups decreased with time since diagnosis, or even disappeared [1, 8, 9, 15]. In our study we also found such a decrease in the differences between the stage groups.
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conclusion |
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TopAbstractintroductionpatients and methodsresultsdiscussionconclusionAcknowledgementsReferences |
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Prognosis for patients with cancer generally improved with each year survived. The good news is that it improves for patients with most tumour types. Patients with colorectal cancer, cutaneous melanoma or stage I breast cancer exhibited hardly any excess mortality after 3–15 years, whereas for patients with other tumours survival remained poorer than for the general population. Insight into conditional survival is especially useful for (ex)patients, who may use this information to plan their remaining life.
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Acknowledgements |
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TopAbstractintroductionpatients and methodsresultsdiscussionconclusionAcknowledgementsReferences |
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This work was carried out with grants from the Dutch Cancer Society (IKZ 2000-2260) and the Muntendam Award of 2005 to JWWC.
Received for publication November 1, 2006. Revision received March 14, 2007. Accepted for publication March 14, 2007.
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References |
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TopAbstractintroductionpatients and methodsresultsdiscussionconclusionAcknowledgementsReferences |
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