The prevalence rate of cancer among adult patients with congenital heart disease (CHD) in North America has not been previously described. The Quebec adult CHD database was used to determine the prevalence rate of cancer among adult patients with CHD measured as the number of adults with CHD and cancer alive in 2005 per 1,000 adults with CHD. This prevalence rate was compared with the prevalence rate of cancer in the general population of adults in Canada. Types of cancer among the CHD group were described by gender and age. Adult patients with CHD had a 1.6 to 2 times higher prevalence of cancer at 2, 5, and 10 years for both men and women. Overall, men had a greater prevalence of total cancers in all-time durations than did women. Breast, colon, and prostate cancer were the most common cancers reported in adults with CHD. In conclusion, we observed an increased prevalence of cancer among the adult CHD population of Quebec compared with the general Canadian population.
As a contribution to our understanding of the cancer risk in adult patients with congenital heart disease (CHD), we sought to determine if a greater prevalence of cancer could be observed in adult patients with CHD compared with the general population in a similar geographic jurisdiction. Given the potential underlying associations between CHD and cancer, including radiation and other environmental exposures and potential genetic predisposition, we hypothesized that adults with CHD have a greater prevalence of cancer than the general population. We performed a population-based analysis of cancer prevalence in adult patients with CHD using the Quebec CHD database with 2 objectives: (1) describing cancer prevalence in the adult CHD population and (2) comparing adult CHD cancer prevalence rates to the Quebec and Canadian general populations.
Methods
In Quebec, Canada, all residents have access to universal health care. Physicians within the province make monetary claims to the government, specifically the Régie de l’assurance maladie du Québec (RAMQ), for remuneration of all diagnostic and therapeutic services provided. All diagnoses, hospitalizations, and medical services an individual receives during their lifetime are recorded in province-wide administrative databases using a unique health care identifier, assigned to each person at birth or on first residency in the province. The provincial medical claims (RAMQ: 1983 to 2005), the provincial hospital discharge database (Med-Echo: 1987 to 2005), and the provincial death registry were merged using the unique patient identifiers, creating the Quebec Congenital Heart Disease Database. This is a longitudinal province-wide patient-level database consisting of demographic, therapeutic, and diagnostic records of all CHD patient encounters with the Quebec health care system from January 1, 1983, to December 31, 2005. CHD defects were classified based on anatomic diagnosis as follows: severe (endocardial cushion defect, Tetralogy of Fallot, univentricular heart, transposition complex, truncus arteriosus, hypoplastic left heart syndrome), shunts (Ebstein’s anomaly, atrial or ventricular septal defects, patent ductus arteriosus, aortic coarctation), valvular (anomalies of the pulmonary artery or valve, anomalies of great veins, congenital tricuspid valve disease, congenital aortic or mitral stenosis, or insufficiency), and other CHD lesions (unspecified anomalies of the heart or aorta). The following co-morbid conditions were identified based on International Classification of Diseases, Ninth Revision , codes and/or procedural codes: congestive heart failure, pulmonary hypertension, atrial fibrillation, and coronary artery disease. Having undergone cardiac surgery was also identified through procedural codes. Permission to receive data from the RAMQ and Med-Echo was received from the Commission d’Acces an l’information du Québec and the research ethics boards of the McGill University Health Center Research Institute. Confidentiality was maintained as patient files were identified by a unique encrypted identification number that was common to both databases.
The Quebec CHD database from 1983 to 2005 is composed of 71,467 patients with CHD. Cancer prevalence estimates from this database were defined as the number of adult patients with CHD (at least 20 years of age) alive on January 1, 2005 (n = 34,965) who were diagnosed with any type of cancer up to December 31, 2004. Patients with CHD <20 years and/or deceased by the index date, January 1, 2005, were excluded from the analysis (n = 35,504), as were patients born after January 1, 2005 (n = 998); 2-, 5-, and 10-year prevalence estimates were calculated based on a diagnosis of cancer during a hospitalization in the Med-Echo database in the 2, 5, or 10 years before January 1, 2005. For instance, the 2-year prevalence was estimated as the number of patients with a primary cancer hospitalization from January 1, 2003, to December 31, 2004, that were alive and an adult on January 1, 2005 (i.e., the index date). In addition, 2-, 5-, and 10-year overall and cancer-specific prevalence rates (per 100,000) were derived for all patients with CHD.
Ellison and Wilkins published cancer prevalence as of January 1, 2005, in the general Canadian population. Prevalence was calculated in 2 ways: the number of people living with cancer on a specified date (person-based prevalence) and the total number of cancer diagnoses in those alive on that date (tumor-based prevalence). All primary invasive cancers were counted. Based on incidence data from the Canadian Cancer Registry linked with mortality data from the Canadian Vital Statistics Death Database and population estimates from Statistics Canada’s Demographics Estimates Compendium 2007, they calculated and reported age-specific, 5-year prevalence proportions for all cancers combined and for each specific cancer type. They also reported 2-, 5-, and 10-year person-based cancer prevalence with age distribution standardized to the World Standard Population.
The first report on cancer prevalence in Quebec population was published in 2005 by the Statistic Institute of Quebec. In the report, prevalence was calculated as the sum of cases of incidence during a given period minus the number of deaths; 5-, 10-, and 15-year cancer prevalence in 1999 was calculated and reported using data from the Quebec Cancer Registry and Quebec Death File. The Quebec Cancer Registry reports hospital data (i.e., data from discharge records from general and specialized care hospitals). All primary cancers were considered in cancer prevalence calculation.
For comparison with the CHD cancer person-based prevalence rates, we used 2-, 5-, and 10-year cancer prevalence for the general population of Canada as of January 1, 2005 (n = 24,366,244). We also compared the CHD cancer prevalence rates with the 5- and 10-year cancer prevalence for the Quebec general population as of December 31, 1999 (n = 5,706,037), so the cancer prevalence in patients with CHD in 1999 was also estimated.
The prevalence rates of cancer in the patients with CHD were compared with that of the general Canadian population in 2005, generating age-standardized prevalence rate ratios (PRRs), for 2-, 5-, and 10-year durations stratified by gender, with p values calculated using the binomial test. Five-year (1995 to 1999) and 10-year (1990 to 1999) overall cancer prevalence proportions in patients with CHD were compared with the equivalent cancer prevalence proportions in the Quebec general population. It was possible for an individual to be diagnosed with multiple different primary cancers during a given time frame, and hence, this patient would contribute to the prevalence estimates for >1 specific cancer type. As a result, cancer-specific prevalence estimates may not sum to the prevalence estimates for all combined cancers. Age-specific 5-year prevalence rates were also presented by cancer site and gender. The distribution of prevalent cancer types during the period 1995 to 2005 were displayed by gender as was the number of prevalent patients of the 10 most common cancers in the patients with CHD. All analyses were performed using SAS software (version 9.3: SAS Institute Inc., Cary, North Carolina).
Results
Of the 71,467 patients in the Quebec CHD database from 1983 to 2005, 34,965 adults were alive on January 1, 2005. Characteristics of these patients are displayed in Table 1 . Patients with valvular and other conditions were older (median ages 47.7 and 57.2 years, respectively) compared with severe CHD and cardiac shunt patients (median ages 31.5 and 38.5 years, respectively). The CHD group does include patients with trisomy 21 that has a known association with leukemia. This trisomy 21 group comprised a small proportion of the CHD adult population (0.5%) and an even smaller proportion of the cancer CHD population (0.1%).
| Variable | Age (median, IQR) | Men | |
|---|---|---|---|
| Adult CHD patients-total | 34,965(100%) | 44.2 (29.8 – 64.2) | 15,097 (43.2%) |
| Age on Jan 1st, 2005 | |||
| 20∼30 years | 8,863(25.3%) | – | 4,130(46.5%) |
| 30∼40 years | 6,103(17.5%) | – | 2,319(38.0%) |
| 40∼50 years | 5,358(15.3%) | – | 2,072(38.7%) |
| 50∼60 years | 4,249(12.2%) | – | 1,986(46.7%) |
| 60∼70 years | 4,023(11.5%) | – | 1,890(47.0%) |
| 70∼80 years | 3,903(11.2%) | – | 1,784(45.7%) |
| 80+ years | 2,466(7.1%) | – | 910(36.9%) |
| CHD type | |||
| Severe | 3,000 (8.6%) | 31.5 (24.5 – 42.4) | 1,284 (42.8%) |
| Shunts | 14,228 (40.7%) | 38.5 (27.6 – 54.4) | 5,683 (39.9%) |
| Valvular | 5,531 (15.8%) | 47.7 (36.2 – 66.9) | 2,635 (47.6%) |
| Other | 12,206 (34.9%) | 57.2 (39.5 – 72.3) | 5,495 (45.0%) |
| Comorbidities | |||
| CHF + PH + AF | 8,067 (23.1%) | 65.9 (48.1 – 76.9) | 3,802 (47.1%) |
| Cardiac Surgery | 8,341 (23.9%) | 59.2 (35.6 – 73.5) | 4,431 (53.1%) |
| Coronary Artery Disease | 1,705 (4.9%) | 70.9 (59.9 – 78.2) | 1,072 (62.9%) |
There were an estimated 1,156 CHD subjects with cancer from 1995 to 2005. Table 2 lists the age-standardized overall and cancer-specific prevalence proportions, by gender, for 2-, 5-, and 10-year durations. Men had a greater prevalence of total cancers in all time durations than did women. Prostate and colorectal cancers were the first and second most prevalent cancers, respectively, in men. Other common cancers among men included lung/bronchus cancer, bladder cancer, and leukemias. In women, breast cancer was the most prevalent cancer in the 2-, 5-, and 10-year durations. In the 2-year duration, lung/bronchus and colorectal cancers were the second and third most prevalent cancer types, respectively. Colorectal cancer surpassed lung/bronchus cancer in prevalence in the 5- and 10-year durations in women. Cancer of the uterine body was also comparatively more prevalent than lung/bronchus cancer in the 10-year duration than in shorter time durations.
| Cancer | Prevalence-duration | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Two-year | Five-year | Ten-year | |||||||
| Both sexes | Males | Females | Both sexes | Males | Females | Both sexes | Males | Females | |
| All cancers | 890.7 | 949.9 | 829.8 | 1,807.1 | 2,237.6 | 1,436.2 | 2,360.2 | 3,048.1 | 2,273.6 |
| Lip, Cavity and Pharynx | 15.4 | 14.4 | 15.8 | 33.4 | 40.9 | 26.8 | 47.1 | 70.4 | 27.8 |
| Esophagus | 3.4 | 7.4 | … | 8.1 | 18.9 | … | 8.1 | 18.9 | … |
| Stomach | 11.0 | 15.8 | 7.7 | 24.4 | 34.6 | 17.4 | 30.0 | 42.1 | 22.1 |
| Colorectal | 102.8 | 116.2 | 89.5 | 193.3 | 243.8 | 151.7 | 281.0 | 358.6 | 213.1 |
| Colon excluding rectum | 69.1 | 79.7 | 59.2 | 138.0 | 161.2 | 119.2 | 196.3 | 223.5 | 172.5 |
| Rectum and rectosigmoid | 33.7 | 36.5 | 30.3 | 55.3 | 82.6 | 32.5 | 84.7 | 135.1 | 40.6 |
| Anus | 2.7 | 5.4 | … | 4.5 | 5.4 | 3.5 | 13.3 | 10.8 | 15.8 |
| Liver | 8.8 | 10.6 | 7.3 | 10.5 | 10.6 | 10.4 | 16.3 | 16.1 | 16.3 |
| Pancreas | 5.8 | 6.9 | 4.7 | 12.5 | 21.1 | 4.7 | 12.5 | 21.1 | 4.7 |
| Larynx | … | … | … | 5.8 | 12.4 | … | 11.7 | 23.2 | 1.6 |
| Lung and bronchus | 109.4 | 101.5 | 112.8 | 154.7 | 178.8 | 130.6 | 177.2 | 209.1 | 146.1 |
| Soft tissue | 24.7 | 36.8 | 16.5 | 36.1 | 36.8 | 36.2 | 56.1 | 44.8 | 67.7 |
| Skin melanoma | 13.9 | 25.9 | 6.3 | 33.8 | 61.4 | 15.1 | 46.4 | 77.4 | 24.5 |
| Breast | 179.2 | 3.5 | 317.8 | 336.0 | 9.0 | 596.1 | 536.0 | 9.0 | 966.7 |
| Cervix uteri | … | … | 5.6 | … | … | 23.5 | … | … | 70.6 |
| Corpus uteri | … | … | 40.0 | … | … | 86.7 | … | … | 183.4 |
| Ovary | … | … | 53.4 | … | … | 74.2 | … | … | 130.7 |
| Prostate | … | 230.8 | … | … | 413.4 | … | … | 575.1 | … |
| Testis | … | 24.9 | … | … | 59.2 | … | … | 86.8 | … |
| Bladder | 58.6 | 86.5 | 36.4 | 111.2 | 175.9 | 57.1 | 163.0 | 267.8 | 76.5 |
| Kidney and renal pelvis | 36.4 | 64.6 | 13.5 | 82.0 | 129.9 | 43.8 | 107.4 | 162.6 | 61.3 |
| Brain and nervous system | 9.2 | 13.6 | 5.4 | 26.0 | 33.3 | 16.4 | 45.3 | 35.3 | 49.7 |
| Thyroid | 11.5 | … | 18.6 | 40.9 | 16.2 | 56.9 | 82.9 | 43.2 | 111.0 |
| Hodgkin lymphoma | 17.9 | 33.3 | 5.4 | 30.0 | 59.8 | 5.4 | 55.4 | 92.6 | 27.1 |
| Non-Hodgkin lymphoma | 40.9 | 34.3 | 46.8 | 74.4 | 84.9 | 67.3 | 106.0 | 136.4 | 81.3 |
| Multiple myeloma | 17.8 | 25.5 | 12.4 | 17.8 | 25.5 | 12.4 | 17.8 | 25.5 | 12.4 |
| Leukemias | 82.6 | 116.7 | 50.2 | 113.1 | 155.0 | 76.0 | 184.3 | 262.0 | 118.3 |
| Other, unknown | 5.6 | 2.0 | 8.9 | 25.2 | 21.2 | 27.2 | 25.8 | 21.2 | 28.2 |
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