Park SM, Kim SY, Earle CC, Jeong SY, Yun YH. What is the most cost-effective strategy to screen for second primary colorectal cancers in male cancer survivors in Korea? World J Gastroenterol 2009; 15(25): 3153-3160 [PMID: 19575496 DOI: 10.3748/wjg.15.3153]
Corresponding Author of This Article
Young Ho Yun, MD, PhD, Division of Cancer Control, National Cancer Center, 809 Madu-dong, Ilsan-gu, Goyang-si, Gyeonggi-do 411-769, South Korea. lawyun08@ncc.re.kr
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Sang Min Park, National Cancer Center, Goyang, Gyeonggi, South Korea; Department of Population and International Health, Harvard School of Public Health, Boston, MA, United States; Department of Family Medicine, Seoul National University Hospital, Seoul National University College of Medicine, Seoul 110-799, South Korea
Sun-Young Kim, Program in Health Decision Science, Department of Health Policy and Management, Harvard School of Public Health, Boston, Massachusetts 02115, United States
Craig C Earle, Division of Population Sciences, Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02108, United States
Seung-Yong Jeong, Department of Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul 110-799, South Korea
Young Ho Yun, Division of Cancer Control, National Cancer Center, Goyang, Gyeonggi-do 411-769, South Korea
ORCID number: $[AuthorORCIDs]
Author contributions: Park SM, Kim SY and Yun YH designed the research; Park SM, Kim SY, and Earle CC performed the research; Park SM, Kim SY, Earle CC, Jeong SY and Yun YH wrote the paper.
Correspondence to: Young Ho Yun, MD, PhD, Division of Cancer Control, National Cancer Center, 809 Madu-dong, Ilsan-gu, Goyang-si, Gyeonggi-do 411-769, South Korea. lawyun08@ncc.re.kr
Telephone: +82-31-9201705
Fax: +82-31-9202199
Received: February 4, 2009 Revised: May 23, 2009 Accepted: May 30, 2009 Published online: July 7, 2009
Abstract
AIM: To identify a cost-effective strategy of second primary colorectal cancer (CRC) screening for cancer survivors in Korea using a decision-analytic model.
METHODS: A Markov model estimated the clinical and economic consequences of a simulated 50-year-old male cancer survivors’ cohort, and we compared the results of eight screening strategies: no screening, fecal occult blood test (FOBT) annually, FOBT every 2 years, sigmoidoscopy every 5 years, double contrast barium enema every 5 years, and colonoscopy every 10 years (COL10), every 5 years (COL5), and every 3 years (COL3). We included only direct medical costs, and our main outcome measures were discounted lifetime costs, life expectancy, and incremental cost-effectiveness ratio (ICER).
RESULTS: In the base-case analysis, the non-dominated strategies in cancer survivors were COL5, and COL3. The ICER for COL3 in cancer survivors was $5593/life-year saved (LYS), and did not exceed $10 000/LYS in one-way sensitivity analyses. If the risk of CRC in cancer survivors is at least two times higher than that in the general population, COL5 had an ICER of less than $10 500/LYS among both good and poor prognosis of index cancer. If the age of cancer survivors starting CRC screening was decreased to 40 years, the ICER of COL5 was less than $7400/LYS regardless of screening compliance.
CONCLUSION: Our study suggests that more strict and frequent recommendations for colonoscopy such as COL5 and COL3 could be considered as economically reasonable second primary CRC screening strategies for Korean male cancer survivors.
Citation: Park SM, Kim SY, Earle CC, Jeong SY, Yun YH. What is the most cost-effective strategy to screen for second primary colorectal cancers in male cancer survivors in Korea? World J Gastroenterol 2009; 15(25): 3153-3160
A recent improvement in cancer survival owing to early diagnosis and advances in treatment has raised the issue of second primary cancers (SPCs) in cancer survivors after their primary treatment[12]. Due to carcinogenic effects of cancer-related treatment, genetic susceptibility or unhealthy behavior such as smoking, alcohol and obesity, cancer survivors are at increased risk for SPCs, not only at the original site but at other sites as well[34]. Recent studies have shown that the age-standardized incidence rate was 2.3 times higher for an SPC than for a first cancer in the Korean general male population[5]. Specifically, the age-standardized incidence rate was about four times higher for second than for first primary colorectal cancers (CRCs)[5]. It is well-known that screening for CRC reduces mortality through detection of malignancy at an earlier, more treatable stage as well as by identification and removal of the precursor lesion, the adenomatous polyp[6]. These findings suggest that more thorough surveillance and screening for second primary CRC is needed for the cancer survivors.
Many previous studies have focused on the cost-effectiveness (CE) of CRC screening in the general population[6–9], and several panels have recommended CRC screening for the general population[10–12]. As the risk of CRC and life expectancy are quite different between cancer survivors and the general population, screening guidelines for the general population could not be applied to the cancer survivors. However, until now, there have been few recommendations for CRC screening for cancer survivors. To suggest a feasible economic strategy of second primary CRC screening for cancer survivors in Korea, we constructed a decision-analytic model, and compared the CE results of cancer screening in cancer survivors and in the average-risk general population.
MATERIALS AND METHODS
The natural history of a simulated male cancer survivors’ cohort was modeled with and without second primary CRC screening until age of 75 years (Figure 1). For simplicity and comparison with results from the general population, we assumed that all male cancer survivors enter at age 50 years, which most guidelines for the general population recommended for starting CRC screening[10–12]. We developed a Markov model using TreeAgePro 2007 software (TreeAge Software Inc., Williamstown, Massachusetts). The Markov model estimated the clinical and economic consequences of eight different screening strategies as follows: (1) no screening, (2) fecal occult blood test (FOBT) annually (FOBT1), (3) FOBT every 2 years (FOBT2), (4) sigmoidoscopy every 5 years (SIG5), (5) double contrast barium enema every 5 years (DCBE5), (6) colonoscopy every 10 years (COL10), (7) colonoscopy every 5 years (COL5), and (8) colonoscopy every 3 years (COL3).
Figure 1 Markov model of second colorectal cancer (CRC) screening in Korean male cancer survivors.
Individuals were placed into health states defined by the presence or absence of a colorectal polyp or second primary CRC (early or advanced) 1 year after the index cancer diagnosis. Cases of positive screening test results were worked up with a colonoscopy, and individuals diagnosed with polyps underwent polypectomy. The probability of perforation was assigned to colonoscopy, sigmoidoscopy, DCBE and polypectomy[81314]. Mortality caused by the risk of perforation was assumed to be 0.02%[914]. Colonoscopy was repeated every 3 years for surveillance after polypectomy[15]. We assumed that 80% of male cancer survivors underwent the initial screening test, independent of whether they were compliant with past tests. The compliance of follow-up or surveillance colonoscopy was assumed to be 100%. We also assumed that 90% of CRCs develop from polyps[1516], and the latent period between early stage and advanced stage was assumed to be 2 years[9]. The relative risk of CRC in Korean male cancer survivors was assumed to be four times higher than that in the general population[5]. Age-specific transition probabilities and prevalence were calculated between normal, polyp, and CRC to yield an incidence rate of polyp and CRC derived from previous literature and the Korea Central Cancer Registry[717–19]. The stage-specific CRC mortality were applied uniformly to all malignancies regardless of the means of detection (by symptoms or screening) or the state of detection (diagnosed vs undiagnosed cancer). Age-specific mortality from index cancer and other causes was estimated based on the above sources combined with statistics published by the National Center for Health Statistics[20] and Korea Central Cancer Registry[21]. As there have been few studies on mortality from second primary CRC, we calculated the additional yearly probability of dying from a second primary CRC based on cancer stage from previous studies of CRC as the first index cancer[21–23].
We obtained the data on the costs of CRC treatment by stage and time period from the National Health Insurance Corporation (social insurer of the national health insurance (NHI) with a universal coverage of population)[24]. Costs of screening tests were obtained from the fee schedule of the National Health Insurance Corporation (the NHI of Korea has a fee schedule applied to all insured services)[25]. Costs were expressed in US dollars and the exchange rate was 955 Korean Won for one US dollar in 2006[26]. As the indirect costs of cancer screening are not established in Korea, we included only direct medical costs.
Our main outcome measures were discounted lifetime costs, life expectancy, incremental cost-effectiveness ratio (ICER), which were compared for different CRC screening strategies. Because there are uncertainties with respect to quality of life associated with CRC screening, colorectal polyp, and second CRC, we conducted the base case analysis using increase in life expectancy as the primary outcome. Incremental CE analysis was performed by ranking the 16 strategies in order of increasing effectiveness. After eliminating strategies that were more or equally costly and less effective than a competing strategy [i.e. ruled out by simple dominance), we calculated the ICER for each strategy (additional cost divided by life-year saved (LYS)] compared with the next least expensive strategy. Strategies exhibiting extended dominance were eliminated from the rank-ordered list, and ICERs of the remaining strategies were recalculated[27]. Future costs and life-years were discounted at an annual rate of 3%. We compared the results from male cancer survivors with that from general male population.
Sensitivity analyses were performed to assess the stability of the results of a plausible range of several parameters, such as prevalence of colorectal polyps at age 50 years, 5-year survival rates of second primary CRC, complications of screening test or polypectomy etc (Table 1). We performed detailed analyses by changing key variables of the index cancer such as 5-year survival rate of first cancer, relative risk of CRC in cancer survivors compared with that in general population. In addition, we evaluated the effects of changing age of subjects for starting second primary CRC screening and compliance rate on the CE of our results.
In the base-case analysis at 80% screening compliance, all screening strategies extended life expectancy both in male cancer survivors and the general population (Table 2). The strategies which were not ruled out by simple dominance nor extended dominance (non-dominated strategies) in the general population were COL10, COL5, and COL3, while those in cancer survivors were COL5 and COL3. The ICER for COL3 in cancer survivors was $5593 per LYS. In cancer survivors, the lifetime total cost per person associated with “FOBT annually” was larger than that associated with no screening, while COL5 and COL3 were less costly than no screening.
Table 2 Cost-effectiveness of colorectal screening strategies among male cancer survivors and the general population in Korea (80% compliance).
Figure 2 shows the results of one-way sensitivity analyses on CE from the perspective of COL3 vs COL5 in male cancer survivors. In most cases, COL5 and COL3 were non-dominated strategies, and the ICER of COL3 ranged between $1480 and $9192.
Figure 2 Sensitivity analyses on cost-effectiveness from the perspective of colonoscopy every 3 years vs colonoscopy every 5 years in male cancer survivors.
Table 3 shows the results of two-way sensitivity analyses by changing risk of second CRC and 5-year survival rate of index cancer in Korean male cancer survivors. If the risk of CRC in cancer survivors was at least three times higher than that in the general population, screening with COL5 in cancer survivors had an ICER of less than $4000 per LYS in the entire range of 5-year survival of index cancer between 20% and 80%. If the risk of CRC in cancer survivors was two times higher than that in the general population, COL5 in cancer survivors had an ICER of less than $10 500 per LYS in both types of index cancer with poor and good prognosis. If the risk of CRC in cancer survivors was the same as that in the general population, non-dominated strategies were no screening, COL10, COL5, and COL3, and the ICER of COL5 was more than $25 000 per LYS, while the ICER of COL10 ranged between $2315 in index cancer with good prognosis and $19 650 in index cancer with poor prognosis.
Table 3 Two-way sensitivity analysis by changing variables of index cancer such as 5-yr survival rate of first cancer and relative risk of colorectal cancer in Korean male cancer survivors.
Relative risk of colorectal cancer in cancer survivor compared with that in general population
Table 4 shows the results of sensitivity analysis by changing compliance of CRC screening and age of cancer survivors for starting CRC screening. If the age of cancer survivors for starting CRC screening was 50 years or older, COL3 had an ICER of less than $14 600 per LYS, regardless of the screening compliance. If age for starting CRC screening in cancer survivors was 40 years, the ICER of COL5 was less than $7400 per LYS saved in all cases of CRC screening compliance.
Table 4 Two-way sensitivity analysis on cost-effectiveness of 2nd primary colorectal cancer screening by compliance of screening and age of Korean male cancer survivors for starting screening.
Age for starting screening
Compliance of 2nd colorectal cancer screening = 60%
Compliance of 2nd colorectal cancer screening = 80%
Compliance of 2nd colorectal cancer screening = 100%
We constructed a computer simulation to suggest economic strategies of second primary CRC screening for cancer survivors in Korea, and compared the CE results of CRC cancer screening in cancer survivors and in the average-risk general population. As all non-dominated strategy were those using colonoscopy in both cancer survivors and the general population, more strict and frequent recommendation of colonoscopy such as COL5 and COL3 could be considered economic strategies for male cancer survivors.
Until now, there has been no explicit threshold of CE below which policy makers will consider accepting the strategy. In the US, a figure of $50 000 per Quality Adjusted Life-Year (QALY) has frequently been quoted for many years as being cost-effective[43]. The World Health Report 2002 suggested that interventions costing less than three times Gross Domestic Product (GDP) per capita for each Disability Adjusted Life-Year (DALY) averted represented good value for money[44], which is usually well in excess of $50 000 per QALY in many high-income countries[43]. In our study, the ICER for COL3 was less than $6000 per LYS in a base line analysis, and did not exceed $10 000 per LYS in one-way sensitivity analyses. Our findings also suggest that if the risk of CRC in cancer survivors is at least two times higher than that in the general population, COL5 could be a cost-effective strategy for second primary CRC screening for cancer survivors of both good and poor prognosis of index cancer, with an ICER of less than $10 500 per LYS. As our primary outcomes are not QALY or DALY, direct comparisons might be difficult. The GDP per capita of Korea was more than $20 000 in 2006. When we approximately applied these CE thresholds, in most cases, COL5 and COL3 could be considered a cost-effective method for second primary CRC screening for Korean male cancer survivors, regardless of the index cancer. Even if the index cancer were CRC, our finding could be applied and be consistent with the CRC surveillance guidelines of the American Society of Clinical Oncology (ASCO)[45]. In ASCO guidelines, routine annual colonoscopies are not recommended for all CRC patients, and colonoscopy every 3-5 years could be sufficient to detect new CRCs and polyps[45].
It is also important to consider the changes in CE of these strategies according to age of starting second primary CRC screening in cancer survivors. Little is known about the CE if cancer survivors start second primary CRC screening above or below age 50, at which most guidelines recommend starting CRC screening in the general population. Our findings suggest that for male cancer survivors in older age, COL3 had more favorable CE results, regardless of screening compliance. For younger cancer survivors aged 40 years old, COL5 could be considered a CE strategy with ICER of less than $7600 per LYS.
Interestingly, in our study of Korea, COL10, COL5 and COL3 had lower total medical costs than no screening of male cancer survivors. In other countries, screening for CRC usually leads to more costs than no screening. Cost estimates for the medical care of CRC treatment in the US range from $25 000 to $70 000 and the cost of COL is about $1000[916]. However, in Korea, the cost estimate of CRC treatment in the first year ranges from $7000 to $14 000 while the cost of COL was about $60[2425]. The ratio of treatment cost to COL cost ranges from 25:1 to 70:1 in the US and 120:1 to 230:1 in Korea. Due to the difference in cost structures, screening with colonoscopy might be more cost-effective in Korea than in other countries. However, CRC screenings are not covered by the Korean NHI scheme in either the general population or cancer survivors. Instead, the Korean government started the national cancer screening program (NCSP) in 1999, which was extended to include CRC screening in 2004[11]. The government covers 50% of the screening cost for the insured and 100% for low-income people. However, the primary method for CRC screening in the Korean NCSP is FOBT annually. Our study shows that the strategy of “FOBT annually” is always the dominant strategy in male cancer survivors, and costs more than the strategy of no screening.
The major barrier to promotion of colonoscopy as a primary CRC screening tool is the lack of manpower to deliver colonoscopy to the public in Korea. In these human-resource limited setting, it is important to identify the more vulnerable population who has a greater potential to receive benefits. Our study suggests that cancer survivors who are at increased risk of second primary CRC have a favorable result of CE of CRC screening compared with the general population. Even in younger cancer survivors aged 40 years old, COL5 might be economically feasible, while COL10 is usually recommended for the Korean general population aged 50 years old. Therefore, at least for cancer survivors, CRC screening should be covered by the Korean NHI scheme and screening methods using colonoscopy are needed to be recommended as a primary screening strategy for CRC in this population.
Limitations
Our analysis has several limitations. In the design of the model, we tried to reduce the complex natural history of CRC to a few essential states and to avoid assumptions on treatments for which little or no published data existed. For instance, we assumed that 90% of second primary CRC arose from polyps. We used several sets of data from the general population, such as prevalence of colorectal polyp by age, polyp recurrence rate, and treatment costs of second primary CRC, if there were no published data available in cancer survivors. There were possible differences between these two populations. However, when we performed sensitivity analyses, the CE results were usually insensitive to the plausible range of these uncertain parameters. Second, we calculated only the direct costs and did not take into account the impact of CRC and screening on indirect costs. Third, in our study, recently developed CRC screening strategies such as CT colonoscopy were not included. However, the cost of CT colonoscopy is about four times higher than that of colonoscopy in Korea, while the sensitivity and specificity of CT colonoscopy is not superior to that of colonoscopy[46], and this new method does not seem to be an economically-efficient strategy.
In conclusion, with an increased population of long-term cancer survivors, effective systems for their health promotion are needed. Implementation of the economic SPC screening program might be one of the important interventions to improve their health. Our study showed that COL3 or COL5 might be suggested as a primary strategy for second primary CRC screening in cancer survivors who have a higher risk of CRC than the general population. This study supports the evidence and rationale for second primary CRC screening in male cancer survivors.
COMMENTS
Background
Recent improvement in cancer survival due to early diagnosis and advances in treatment has raised the issue of second primary cancers (SPCs) in cancer survivors after their primary treatment. The age-standardized incidence rate is about four times higher for second primary colorectal cancer (CRC) than for first primary CRC in Korea. However, until now, there have been few recommendations and economic evaluations of CRC screening for cancer survivors.
Research frontiers
To suggest a feasible economic strategy of second CRC screening for cancer survivors in Korea, the authors constructed a decision-analytic model, and compared the cost-effectiveness results of cancer screening between in male cancer survivors.
Innovations and breakthroughs
Non-dominated strategies were those using colonoscopy in both cancer survivors and the general population, and more strict and frequent recommendations for colonoscopy (COL) such as COL5 (screening every 5 years) and COL3 (screening every 3 years) could be considered as economic strategies for male cancer survivors.
Applications
The major barrier to promoting colonoscopy as a primary CRC screening tool is the lack of manpower to deliver colonoscopy to the public in Korea. In these human-resource limited settings, it is important to identify the most vulnerable population who has more potential to receive the benefits. In younger cancer survivors aged 40 years old, COL5 might be economically feasible, while COL10 is usually recommended for the Korean general population aged 50 years old. Therefore, at least for cancer survivors, CRC screening should be covered by the Korean national health insurance scheme and screening methods using colonoscopy should be recommended as a primary screening strategy for CRC in this population.
Terminology
SPC: A SPC is a new primary cancer developing in a person with a history of cancer.
Peer review
The authors investigated the cost-effective strategy of CRC screening for cancer survivors in Korea. The article is well written and the contents are reliable.
Footnotes
Supported by Takemi Program in International Health at Harvard School of Public Health and by National Cancer Center Grant, No. 07104221
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