G astric cancer is the sixth most common cancer and an important cause of cancer-related deaths worldwide [1]. According to cancer statistics in Turkey, gastric cancer is the 5 th most common cancer both in men and women [2]. Genetic and environmental risk factors are responsible for the etiology of gastric cancer. Among those smoking, alcohol usage, smoked and salted foods, helicobacter pylori infection, pernicious anemia, chronic atrophic gastritis, intestinal metaplasia, previous gastric operations, peutz-jeghers syndrome, li-fraumeni syndrome and hereditary diffuse gastric cancer syndrome are the most important ones [3-6]. International Union against Cancer/American Joint Committee on Cancer (UICC/AJCC) TNM stage is the most important determinant of prognosis after surgery [7]. Studies reported that there are also many other prognostic factors that affect survival, such as lymphovascular invasion, grade, resection type and performance status [8, 9].

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BackgroundDecrease in bone mineral density, osteoporosis development, bone toxicity and resulting insufficiency fractures as late effect of radiotherapy are not well known. Osteoporosis development related to radiotherapy has not been investigated properly and insufficiency fractures are rarely reported for vertebral bones.MethodsNinety-seven patients with gastric adenocarcinoma were evaluated for adjuvant treatment after surgery. While 73 out of 97 patients treated with adjuvant chemoradiotherapy comprised the study group, 24 out of 97 patients with early stage disease without need of adjuvant treatment comprised the control group. Bone mineral densities (BMD) of lumbar spine and femoral neck were measured by dual energy x-ray absorptiometry after surgery, and one year later in both groups.ResultsThere was statistically significant decline in BMDs after one year in each group itself, however the decline in BMDs of the patients in the irradiated group was more pronounced when compared with the patients in the control group; p values were 0.02 for the decline in BMDs of lumbar spine, and 0.01 for femoral neck respectively. Insufficiency fractures were observed only in the irradiated patients (7 out of 73 patients) with a cumulative incidence of 9.6%.ConclusionsAbdominal irradiation as in the adjuvant treatment of gastric cancer results in decrease in BMD and osteoporosis. Insufficiency fracture risk in the radiation exposed vertabral bones is increased. Calcium and vitamin D replacement and other measures for prevention of osteoporosis and insufficiency fractures should be considered after abdominal irradiation.

BackgroundVolumetric shrinkage of normal tissues such as salivary glands, kidneys, hippocampus are observed after radiotherapy. We aimed to assess the alterations in pancreatic volume of patients who received abdominal radiotherapy and define pancreas as an organ at risk for radiation treatment planning.Material-methodsForty-nine patients operated for gastric adenocarcinoma who received adjuvant abdominal radiotherapy were in the study group, 27 patients with early stage disease who did not need adjuvant treatment after surgery comprised the control group. An experienced radiologist contoured the pancreas of all the patients from computed tomographies imported to the planning system obtained either for radiation planning purpose or for follow-up after surgery. The same procedure was repeated one year later for both groups. Measured volume of the pancreas was expressed in cm3.ResultsMean pancreatic volumes were similar in both groups at the onset of the study, 51,34 ± 20,33 cm3, and 50,12 ± 23,75 cm3 in the irradiated and the control groups respectively (p = 0,63). One year later, mean pancreatic volumes were significantly decreased in each group; 22,48 ± 10,53 cm3, 44,18 ± 23,08 cm3 respectively, p < 0,001. However, the decrease in pancreatic volume was significantly more pronounced in the irradiated group in comparison to the control group, p < 0,001.ConclusionVolumetric decrease in normal tissues after radiotherapy is responsible for loss of organ function and radiation related late side effects. Although pancreas is a radiation sensitive organ losing its volume and function after radiation exposure, it is not yet considered as an organ at risk for radiation treatment planning. Pancreas should be contoured as an organ at risk, dose-volume histogram for the organ should be created, and safe organ doses should be determined. This is the first study declaring pancreas as an organ at risk for radiation toxicity and the necessity of defining dose constraints for the organ.