Colorectal carcinoma is a cancer of the large intestine (colon carcinoma) or rectum (rectal carcinoma) and is one of the most common malignant tumours. Worldwide, colorectal cancer is the fourth most common cancer. However, the incidence has decreased or stabilized, especially among older people. This is mainly due to preventive measures. In Germany, colorectal cancer screening by stool tests has been offered since 1977 and colonoscopy since 2002. The 5-year survival rate in Germany is 62 percent for women and 63 percent for men, and the trend is rising. Despite these improved survival rates, an increase in second primary cancers after a first cancer is to be expected, especially among younger survivors, in whom colorectal cancer is increasingly occurring at an early stage (under 50 years of age). The overall survival rate is significantly worse in this group, possibly due to the development of multiple cancers.

The Chair of Epidemiology, headed by Prof. Dr. Stefanie Klug, has therefore looked at how many survivors of colorectal cancer develop cancer again and conducted an analysis as part of co-author Ying-Ju Tseng's master's thesis (MSc Epidemiology, LMU). The results have now been published under the title "Second primary cancer among 217702 colorectal cancer survivors: A analysis of national German cancer registry data" in the "International Journal of Cancer". The journal has an impact factor of 7.316.

The results are based on data from nine German cancer registries, which cover 37 percent of the German population. All colorectal cancers between 1990 and 2011 and second cancers that occurred up to 2013 were included. A total of 217,702 cases were included in the study. Of these, 18,751 developed cancer again after an average of about three and a half years, with the average age being 69 years.

"We wanted to investigate how high the risk of a second primary cancer is after surviving colorectal cancer," explains Linda Liang, Research Associate at the Chair of Epidemiology and first author of the publication. "In addition, we wanted to find out in which organs, i.e. in which part of the body, these second cancers occur. In doing so, we found that the risk of second primary cancer increases significantly, especially in the younger cohorts."

Patients who developed colorectal cancer under the age of 50 had a fourfold higher risk of second cancer development. In addition, the overall risk of cancer was significantly higher in colorectal cancer survivors than in the general population. In particular, the digestive system, the urinary system and the female and male reproductive organs were common sites for second cancer development.

"Our data was limited in the investigation of why these second cancers develop. However, we did analyze whether the effects of treatment of the colorectal cancer would affect the development of these second cancers. As part of the study, we looked at the effect of chemotherapy and radiotherapy. We did not find any particular increase in risk, but we did find a difference between those who had colorectal cancer and rectal cancer," Liang said.

"We are glad to be able to use these data from the cancer registries, which are compiled at the Center for Cancer Registry Data (ZfKD) at the Robert Koch Institute (RKI). Data collection in cancer registries in Germany has improved a lot and will certainly continue to develop in the future," says Prof. Klug. "However, the data currently available offers limited information to make really robust detailed evaluations. Therefore, early and targeted surveillance of certain subgroups of colorectal cancer survivors should be improved. It will also be necessary to update the relevant clinical guidelines for subsequent cancer follow-up, taking into account patient characteristics and disease status."

To the homepage of the Chair of Epidemiology

To the publication "Second primary cancer among 217702 colorectal cancer survivors: A analysis of national German cancer registry data“ in the "International Journal of Cancer“

Kontakt:

Prof. Dr. Stefanie Klug
Lehrstuhl für Epidemiologie
Georg-Brauchle-Ring 56
80992 München

Telefon: 089 289 24950
E-Mail: stefanie.klug(at)tum.de

Linda Liang
Lehrstuhl für Epidemiologie
Georg-Brauchle-Ring 56
80992 München

Telefon: 089 289 24
E-Mail: linda.liang(at)tum.de

Text: Romy Schwaiger
Fotos: “International Journal of Cancer”/Astrid Eckert/TUM/privat