Italian cancer figures, report 2013: Multiple tumours.

OBJECTIVES

This collaborative study, based on data collected by the network of Italian association of cancer registries (AIRTUM), provides updated estimates on the incidence risk of multiple primary cancer (MP). The objective is to highlight and quantify the bidirectional associations between different oncological diseases. The quantification of the excess or decreased risk of further cancers in cancer patients, in comparison with the general population, may contribute to understand the aetiology of cancer and to address clinical follow-up.

MATERIAL AND METHODS

Data herein presented were provided by AIRTUM population-based cancer registries, which cover nowadays 48% of the Italian population. This monograph utilizes the AIRTUM database (December 2012), considering all malignant cancer cases diagnosed between 1976 and 2010. All cases are coded according to ICD-O-3. Non-melanoma skin cancer cases, cases based on death certificate only, cases based on autopsy only, and cases with follow-up time equal to zero were excluded. To define multiple primaries, IARC-IACR rules were adopted (http://www.iacr.com.fr/MPrules_july2004.pdf). Data were subjected to standard quality control procedures (described in the AIRTUM data management protocol) and specific quality control checks defined for the present study. A cohort of cancer patients was followed over time from first cancer diagnosis until the date of second cancer diagnosis, death, or the end of follow-up, to evaluate whether the number of observed second cancer cases was greater than expected. Person years at risk (PY) were computed by first cancer site, geographic area (North, Centre, South and Islands), attained age, and attained calendar-year group. All second cancers diagnosed in the cohort's patients were included in the observed numbers of cases. The expected number of cancer cases was computed multiplying the accumulated PY by the expected rates, calculated from the AIRTUM database stratified by cancer site, geographic area, age, and calendar-year group. The Standardized Incidence Ratio (SIR) was calculated as the ratio of observed to expected cancer cases. The Excess Absolute Risk (EAR) beyond the expected amount were calculated subtracting the expected number of subsequent cancers from the observed number of cancer cases; the difference was then divided by the PY and the number of cancer cases in excess (or deficit) was expressed per 1,000 PY. Confidence intervals were stated at 95%. The two months (60 days) after first cancer diagnosis were defined as "synchronicity period", and in the main analysis observed and expected cases during this period were excluded. It was estimated the excess risk in the period after first diagnosis (≥ 0 months), excluding the synchronicity period (≥ 2 months), and during the following periods: 2-11, 12-59, 60-119 and 120 months after diagnosis. First-cancer-site-and-gender-specific sheets are presented, reporting both SIRs and EARs.

RESULTS

For 5,979,338 person-years a cohort of 1,635,060 cancer patients (880,361 males and 754,699 females) diagnosed between 1976 and 2010 was followed. The mean follow-up length was 14 years. Overall, 85,399 metachronous (latency ≥2 months) cancers were observed, while 77,813 were expected during the study period: SIR: 1.10 (95%CI 1.09-1.10), EAR: 1.32 x 1,000 person-years (95%CI 1.19 - 1.46). The SIR was 1.08 (95%CI 1.08-1.09) for men (54,518 observed and 50,260 expected) and 1.12 (95%CI 1.11-1.13) for women (30,881/27,553), and the EAR 1.61 (95%CI 1.37-1.84) and 1.08 x 1,000 person-years (95%CI 0.93-1.24), respectively.Moreover, during the first two months after first cancer diagnosis (synchronous period) 14,807 cancers were observed while 3,536 were expected (SIR: 4.16; 95%CI 4.09-4.22); the SIR was 4.08 (95%CI 4.00-4.16) for men and 4.32 (95%CI 4.20-4.45) for women.The mean age of patients at first cancer diagnosis was 67.0 years among males and 65.8 among females.The risk of MP was related to age being higher for younger patients and lower for older ones. In relation to the time of first cancer diagnosis, the SIR was very high at the beginning and then decreased, although remaining constantly over 1, and then rose over time. No strong differences were evident across the different incidence periods, which all showed an increased MP risk.Women had higher SIRs than expected for 18 cancer sites, men for 12. The statistically significantly SIRs lower than 1 were 2 and 8, respectively. Increased overall MP risk was observed for patients of both sexes with a first primary in the oral cavity (SIR men: 1.93; SIR women: 1.48), pharynx (SIR men: 2.13; SIR women: 1.99), larynx (SIR men: 1.57; SIR women: 1.79), oesophagus (SIR men: 1.45; SIR women: 1.41), lung (SIR men: 1.09; SIR women: 1.13), kidney (SIR men: 1.14; SIR women: 1.15), urinary bladder (SIR men: 1.29; SIR women: 1.22), thyroid (SIR: 1.22 in both sexes), Hodgkin lymphoma (SIR men: 1.59; SIR women: 1.94), and non-Hodgkin lymphoma (SIR men: 1.13; SIR women: 1.12), and for the heterogeneous group "other sites" (SIR men: 1.09; SIR women: 1.07). Moreover, men had a higher MP risk if the first cancer was in the testis (SIR: 1.24), while the same was true for women with gallbladder (SIR: 1.21), skin melanoma (SIR: 1.17), bone (SIR: 1.41), breast (SIR: 1.12), cervix uteri (SIR: 1.23) and corpus uteri (SIR: 1.23), and ovarian cancer (SIR: 1.18). On the contrary, a first liver or pancreas cancer were associated with a decreased MP risk in both sexes (liver SIR: 0.86 and 0.81 for men and women, respectively; pancreas SIR: 0.70 and 0.78 for men and women, respectively), as were those of colon (SIR: 0.93), rectum (SIR: 0.83), gallbladder (SIR: 0.80), prostate (SIR: 0.93), mesothelioma (SIR: 0.65), and central nervous system (SIR: 0.82) among men. Among the cancers for which the EAR is statistically significant, those with higher Excess Absolute Risk of MP were those of the oral cavity (EAR: 16.0 x 1,000 person-years in men and 5.4 in women), pharynx (17.6 and 9.1), larynx (11.4 and 8.8), and oesophagus (8.5 and 4.8).

DISCUSSION

This descriptive study provides quantitative information on the risk of developing a second cancer in an Italian population-based cohort of approximately 1.65 million cancer patients, compared to the risk of the general population. During the follow-up time (on average 14 years) cancer patients had an MP risk that was 10% higher in comparison to the general population and an Excess Absolute Risk of 1.32 x 1,000 person-years. Study of MPs and their risk measures are dependent on methods used in the calculation. The definition of MP is not univocal and using different rules can greatly change the number of cancers in a patient with MPs. However, the AIRTUM cancer registries adopt the same recommendations for MP definition. This monograph was therefore made possible by the shared rules and standards used by AIRTUM registries. The cancer site-specific sheets, which represent the core of the monograph, can be useful to highlight and quantify the bidirectional associations among different diseases and therefore provide indications for clinical follow-up. Lifestyle changes in more healthful directions can have a positive effect in the cancer patient population and should always be recommended.