Second primary malignancy risk among patients with gastric cancer: a nationwide population-based study in Taiwan

Abstract

Patients with gastric cancer are at increased risk of developing SPM. Close surveillance of patients with risk factors over a longer period should be considered.

Risk of second primary cancers among patients with a first primary gastric cancer: A population-based study in North Portugal

“…In published research, the frequency of finding SPC accompanying gastric cancer is higher in male patients [24,27,28], in accordance with our findings. Although SPCs have been related to age [24,28,32], we found no differences between age at diagnosis in patients with and without SPC. Additionally, there were no significant differences in the tumour site of the gastric FPC.…”

“…The proportion of SPCs diagnosed in patients with gastric FPC in Northern Portugal was higher than the observed in Sweden, where 962 (2.8%) SPCs were reported in 34506 people with gastric cancer diagnosed from 1960 to 1981 and followed to December 31, 1981 [23], a longer period than that of our study. On the other hand, our results are consistent with those from Taiwan, where over 2000 SPCs were observed during a follow-up of 47729 gastric FPC patients diagnosed between 1997 and 2011 [24]. In the USA, among 33720 gastric FPC patients diagnosed from January 1992 to December 2012, 1838 patients (5.5%) developed metachronous SPCs after a period of six months from diagnosis [25].…”

“…Compared to the general population, gastric FPC patients had a significantly increased risk of metachronous SPCs, especially in other digestive organs, which remained even when defining these SPCs as more than one year post diagnosis of the FPC. Although some national studies analysing SPCs in gastric cancer patients have been conducted in Sweden [23], Taiwan [24] and the USA [25], comparisons are difficult because of the varying diagnostic and follow-up times, and most other studies are from single-institutions, often with few SPCs. The proportion of SPCs diagnosed in patients with gastric FPC in Northern Portugal was higher than the observed in Sweden, where 962 (2.8%) SPCs were reported in 34506 people with gastric cancer diagnosed from 1960 to 1981 and followed to December 31, 1981 [23], a longer period than that of our study.…”

“…This may be partially explained by improvements in survival of cancer patients overtime [6,7] and the previous study only had follow-up of patients from a single oncology specialized hospital, while our results are from a population-based cancer registry. In general, the proportion of SPCs that are synchronous varies from 11.4 to 47.9% [19,24], using a two month and a one year definition, respectively. We found less than one-third synchronous SPCs using a two month definition, while almost half of all SPCs were diagnosed within the first year of the gastric FPC.…”

“…The guidelines chosen to diagnose SPC may account for some of the heterogeneity observed; compared to the Surveillance, Epidemiology, and End Results Program coding rules, IARC/IACR rules are less complex, have not changed over time and report fewer multiple primary cancers [30]. The best interval to define SPCs as synchronous or metachronous has also been disputed, ranging from one month to one year [8,24,31]. Thus, we may have observed a smaller number of SPCs by using the more restrictive IARC/IACR rules; using a two month gap to classify tumours likely increased the proportion of metachronous SPCs.…”