Gastrectomy is the standard surgical treatment for advanced-stage gastric cancer, and pancreatoduodenectomy is also considered for gastric cancer with pancreatic and duodenal invasion. However, pancreatoduodenectomy is rarely performed for gastric cancer because of significant morbidity and mortality and poor prognosis [7, 8]. Although recent reports have shown that the long-term prognosis is improving [9,10,11,12], the efficacy of pancreaticoduodenectomy for gastric cancer is limited, and the mortality rate of gastric cancer is still high. If the resection margin is positive, pancreaticoduodenectomy may be considered in younger patients without noncurative factors. However, in older patients, as in this case, the benefit is more limited, and the risk is higher [5, 6]. In this case, chemotherapy could prevent pancreaticoduodenectomy and facilitate gastrectomy, resulting in a less invasive treatment.

Laparoscopic surgery is becoming the standard treatment for advanced-stage cancer; however, it is still not common in T4b cases. Yu Pan et al. reported that there is no difference in the volume of blood loss and surgical time. The complication rate and length of hospital stay of elderly patients are longer than those of younger patients [13]. Hence, laparoscopic surgery has several advantages considering the invasiveness of the procedure. The minimally invasive approach for advanced-stage gastric cancer with multiple invasions to other organs can enable us to make a minor adjustment in the cutting line via the magnification effect and to resect surrounding organs within a minimal range.

In Japan, postoperative chemotherapy is the standard treatment for stage II/III gastric cancer, and several cases of postoperative chemotherapy have been collected [14, 15]. However, it challenging to sufficiently administer chemotherapy after surgery in older patients with gastric cancer because of decreased oral intake. Moreover, in some cases, postoperative chemotherapy is impossible because of complications. Although preoperative chemotherapy for locally advanced-stage gastric cancer is not common yet [16], it is easier to administer sufficient chemotherapy preoperatively compared with postoperative chemotherapy and can improve the cure rate [17].

The use of chemotherapy should be reduced or discontinued in some cases based on renal function and general condition. However, if the patient’s poor general condition is attributed to the tumor, chemotherapy may improve the general condition [18]. In this case, when the patient was initially referred to our department, chemotherapy and surgery were considered challenging. However, PS was believed to be declining because of cancer progression, and chemotherapy was administered in anticipation of surgery, which improved the patient’s PS and made surgery possible. It was a marginal lesion that may or may not be resectable, and there may have been an aspect of induction chemotherapy. In addition, the combination of rehabilitation and nutritional management using oral nutritional supplements in the hospital may have contributed to the improvement in his general condition.

In the present case, the patient developed aspiration pneumonia after surgery. Although the patient's symptoms improved with systemic management using antibiotics, the postoperative immunocompromised state of the patient by preoperative chemotherapy may put him at risk for various complications, including aspiration pneumonia. The risk of complications is expected to increase with advancing age, and complications may also reduce postoperative systemic status, leading to decreased ADL and a poorer long-term prognosis.

Considering that the patient was able to ingest orally, SOX was started as preoperative chemotherapy in this case. However, if oral intake is difficult, FOLFOX may be selected as preoperative chemotherapy. Laparoscopic distal gastrectomy with combined resection of the transverse colon was performed; however, if the patient had severe duodenal and pancreatic invasion and the general condition allows it, pancreaticoduodenectomy should be considered. However, if the duodenal or pancreatic invasion is so severe that gastrectomy is difficult, it may be necessary to focus on postoperative chemotherapy. There is no sufficient evidence on the outcomes, advantages, and disadvantages of preoperative chemotherapy. Hence, more cases should be evaluated in the future.