In this study, GBC patients were first divided into a young group (≤ 65 years old) and an elderly group (> 65 years) according to fitting curves between age and OS. Most of the GBC patients were in the elderly group (64.6%). Comparison between the two age groups revealed that more GBC patients older than 65 years old were white, possibly because white patients tend to have better access to health care and are more likely to have a longer life span than are individuals of other races [15, 16]. Additionally, the proportion of patients over 65 years old who were married (1471/3263, 47.15%) was significantly lower than that in the young group (1010/1790, 59.45%), which may be due to the high mortality rate for spouses in that age range. Prognostic analysis demonstrated that being unmarried is unfavorable for survival among elderly GBC patients, which agrees with many previous studies [17–20]. The results indicate that elderly people who lack care from a marriage partner have a poor prognosis.
Further analysis revealed that the proportion of AJCC stage II or IIIA, T2, N0 and M0 stage was decreased in elderly GBC patients. These results can be attributed to the frequent routine check-ups of elderly patients, which can allow for the early diagnosis of disease. The AJCC stage has also been proven to be an independent prognostic factor for OS in elderly GBC patients. It is worth noting that the AJCC subdivides the T2 stage into T2a and T2b, stages with diagnosis and treatment that have been the subject of intense discussion and debate . The controversy lies in the fact that in the clinical setting, the GBC T2 stage can be divided into various substages, such as IIA, IIB, IIIB, and IVB, and might be treatable . Therefore, the results indicate that as a particular group, more clinical attention should be paid to the elderly group of GBC patients.
Moreover, our study indicated a higher overall mortality rate for the elderly group, though the cancer-specific mortality rate was similar to that of the young group. The reason may be that the older the cancer patient is, the more basic diseases he or she has and the more likely he or she will die from these diseases . Therefore, clinical workers should pay more attention to systemic conditions and basic diseases when treating elderly GBC patients.
Treatment data indicated that patients over 65 years old were less likely to receive all kinds of treatment, such as surgery, lymph node dissection, radiation, and chemotherapy. Nonetheless, surgery and chemotherapy were the main forms of treatment, and radiation was obviously applied less often. Further analysis suggested that radical surgery (surgery with lymph node dissection) and chemotherapy have the greatest therapeutic benefit for patients, and they are the main treatment option for GBC [4, 13, 22–27]. Gemcitabine combined with cisplatin was the standard of care for GBC in 2010; however, recent phase III studies support alternatives such as gemcitabine in combination with oxaliplatin or S1 . Systemic therapy is the only option for those diagnosed with an advanced, unresectable stage . Although radiotherapy had a positive impact on OS in univariate analysis, no correlation with OS in multivariate analysis was observed. Such a result may be attributed to the lower sensitivity of GBC to radiotherapy [22, 28, 29].
There are many differences between elderly and young individuals, indicating that elderly GBC patients are a special group of individuals. To better evaluate the prognosis of this distinct population, a nomogram for the prediction of OS were constructed. In addition, due to the high degree of malignancy of GBC, patients often have a short survival time once diagnosed. We developed prediction evaluation models for 1 year and 3 years by combining all independent predictors (marital status, histological type, AJCC stage, lymph node dissection and chemotherapy) to predict OS. To the best of our knowledge, to date, no nomogram has been constructed specifically for elderly GBC patients. Our constructed prognostic nomogram showed good discrimination and predictive accuracy for this special group of GBC patients based on a population-based cohort.
Our study had several main limitations. The relatively incomplete clinical information hindered further evaluations of treatment in the elderly patients. For example, data were lacking for many of the patients, including T stage, N stage, and AJCC stage. Information on the specific chemotherapy regimen used, detailed surgical scope and procedure, and radiation dose also were not available. Therefore, alternative explanations for some of the findings of the present study cannot be ruled out. Nevertheless, our findings will be useful for assessing prognosis in elderly GBC patients and in establishing treatment policies.