One of the biggest challenges in healthcare is the ageing population; in 2015, the life expectancy at birth was 82.9 years, with males expected to live to 80.5 years old and females expected to live to 85.1 years old. Elderly CRC patients are regarded as a special population with unique clinicopathological characteristics, and the increase in comorbidities typically observed in this population tend to increase the potential risk during the perioperative period. In addition, BMI has been previously reported to be associated with the incidence of postoperative complications and even the prognosis of colorectal cancer[17–20]. In the present study, to clarify the effect of BMI on the technical feasibility and oncological safety of radical surgery and the prognosis of CRC in elderly patients, we compared the short- and long-term outcomes between elderly patients in the control group and overweight group.
Along with the increase in material wealth, the incidence of obesity has increased and become a medical and social problem. It has been previously confirmed that obesity increases the difficulty of CRC surgery and the incidence of postoperative complications[17, 19, 21]. A study involving 792 patients with low rectal cancer conducted by Zhang et al. showed that the operation time and length of postoperative hospital stay in the overweight group were significantly longer than those in the control group, and the increase in BMI was closely related to the incidence of postoperative complications such as pneumonia, anastomotic leakage, allergy and incisional hernia[21]. However, the results of the present study show that the increase in BMI does not affect the surgical results, such as the operation time (153.0 vs 142.3, P = 0.226) and intraoperative blood loss (67.8 vs 69.3, P = 0.873). At the same time, the incidence of overall postoperative complications (29.4% vs 25.1%, P = 0.358) and grade 3–4 complications (11.1% vs 14.6%, P = 0.326) in the overweight group did not increase significantly, which differs from that reported in the literature. This may be because a higher proportion of patients in the obesity group underwent laparoscopic surgery (64.7% vs 49.8%, P = 0.004), thus speeding up postoperative recovery and reducing the possibility of complications.
The safety of radical surgery for elderly patients with colorectal cancer is a concern for surgeons. Prior works have reported that the incidence of overall complications in elderly patients with CRC after radical surgery is 9.9%-25.4%, and the incidence of grade 3–5 complications is 6.5%-20.1%[22–25]. Our study showed that the incidence rates of overall complications, grade 1–2 complications and grade 3–4 complications were 40.1%, 26.9% and 13.2%, respectively, which were consistent with previous reports in the literature. In addition, this study revealed that the most common overall complication after radical resection of elderly patients with CRC is abdominal abscess (8.6%), and the most common grade 3–4 postoperative complication is urinary retention (2.4%). Therefore, in view of the above complications, more attention should be given to aseptic operation and the appropriate prolongation of antibiotic use after radical resection of CRC in elderly patients.
Obesity is clearly associated with the incidence of CRC[26], and the relationship between obesity and colorectal cancer has been previously reported but remains controversial. Several studies believe that a high BMI is associated with a poor prognosis in patients with CRC[18, 27], while some studies believe that a high BMI is not related to prognosis[28, 29] or even related to a better prognosis[30, 31]. This study explores the prognostic factors related to elderly patients with CRC after curative resection, and the results show that BMI (HR: 2.30; 95% CI, 1.27–4.17; P = 0.046) and N stage (HR: 2.97; 95% CI, 1.48–5.97; P = 0.002) were independent prognostic factors affecting CCS. Scarpa et al. grouped 595 CRC patients based on BMI and conducted postoperative follow-up. Multivariate analysis showed that BMI > 30 kg/m2 was an independent risk factor for prognosis and recurrence after surgery (HR: 2.2; 95% CI, 1.3–3.9; P = 0.003)[32]. Doria-Rose et al. obtained similar results: those with a high BMI, especially BMI > 35 kg/m2, had a higher recurrence rate and poorer overall survival than those with a normal BMI[33]. The results of the above studies were basically consistent with our findings.
The most significant limitation of the present study is its retrospective nature, and only 372 patients were included, which may have caused some inherent selection bias. In addition, compared to rectal cancer, colon cancer is more likely to cause systemic consumption and lower BMI, and we did not calculate colon and rectal cancer separately. Therefore, multicentre, large-scale, prospective studies are warranted to verify our results.
In conclusion, the results of our study demonstrated that radical resection for CRC is safe and feasible for patients over 80 years of age. An increase in BMI does not increase the difficulty of surgery or postoperative complications. BMI and N stage were independent prognostic factors for elderly CRC patients after radical resection.