After curative gastrectomy for gastric cancer, most patients experience weight loss of about 10–20%; after passing a nadir, weight stabilizes or increases at about 12 months after surgery[13, 14]. Weight loss is attributable to reduced food retention in the stomach, and poor intestinal digestion caused by upper gastrointestinal tract dysfunction; this triggers post‐gastrectomy syndrome and malnutrition[15]. Consistent with previous studies, we found that the average weight loss was about 10% at 1 year after surgery (data not shown). Only 1% of patients experienced continuous postoperative weight gain. Except for such cases, most of the weight change in the first year after surgery was confirmed to be a decrease.
Weight loss after gastrectomy negatively affects quality of life and is associated with dismal survival rates[6, 16]. It is essential to identify patients who are expected to lose weight continuously or to experience difficulty in weight recovery; appropriate clinical intervention can improve their quality of life and prognosis. We are the first to construct a nomogram to predict weight change; we measured the weights of a large retrospective cohort before and after surgery. This nomogram elucidates long-term weight change after surgery, individualizes the weight-gain probability, and facilitates personalized medicine. Again, the model is fast, free, and online.
We found that age, sex, BMI, ECOG performance status, the extent of resection, disease severity, and weight change at 1 year after surgery predicted weight recovery 5 years after surgery. Changes in the levels of Hb, albumin, and ferritin, and the TIBC, also reflected weight changes after gastrectomy. Elderly patients with gastric cancer lose more lean body mass than do others[4]. Older age and total gastrectomy are independent risk factors for post-gastrectomy malnutrition[17]; our findings are consistent with this notion. Patients who underwent total gastrectomy with a higher baseline BMI lost significantly more weight than those of subtotal gastrectomy with lower baseline BMI[13, 18, 19]. We found that subtotal gastrectomy patients evidenced better weight recovery than total gastrectomy patients, perhaps because of better calorie intake, less functional impairment, and a lower blood ghrelin level[20-23].
We found a more significant relationship between male (compared to female) sex and post-gastrectomy body weight loss after subtotal gastrectomy; males have been reported to be more susceptible than females to lean-body-mass loss after gastrectomy[15, 24]. Consistent with previous studies, we found that females exhibited a higher probability of weight recovery than did males. Any relationship between sex and weight recovery after gastrectomy is not fully established. However, we hypothesize that the reasons for lower weight loss after gastrectomy in women are that on average women are lighter than men and have a lower BMI, and show better treatment compliance[25].
Advanced cancer is associated with preoperative cachexia, aggressive tumor behavior, and an increased tumor burden[26]. Cachexia is more negatively prognostic than is simple sarcopenia after radical gastrectomy to treat advanced gastric cancer[27]. When malignant lesions are radically resected, the tumor burden is eliminated, and the probability of weight recovery is thus expected to be high. As we excluded cases with recurrence during follow-up, we suggest that recovery from cachexia was successful.
Albumin is a prognostic tumor marker that has been of great interest; its level is closely related to nutritional and inflammatory status. The albumin level is a component of the prognostic nutritional index (PNI), the controlling nutritional status (CONUT) score, and the nutritional risk index (NRI) commonly used for nutritional evaluation after gastrectomy[17, 28, 29]. Albumin levels tend to recover for up to 5 years after surgery, reflecting weight recovery[30]. Therefore, if the albumin level at 1 year after surgery is maintained or increased, nutritional status is improving, and the probability of weight recovery is increased.
Various types of anemia can occur after gastrectomy; most are attributable to iron deficiency, abnormal vitamin B12 metabolism, or a combination thereof[19]. The most efficient test of iron deficiency is the serum ferritin assay; the total iron-binding capacity (TIBC) is prognostic of such deficiency[31, 32]. We measured the Hb and ferritin levels, and the TIBC; the latter two parameters are major components of our weight-change-prediction model.
The nomogram-calculated probability of weight gain ranged from 10% to about 80%. It is important that clinicians seek factors that increase the probability of weight gain (excluding unmodifiable clinicopathological factors) during outpatient follow-up. We developed a freely available Web-based version of our weight-prediction method; the results are immediate. Non-medical personnel can obtain minimum and maximum risks when patients and caregivers lack access to laboratory findings. According to the model, if an elderly obese male who is not physically active loses weight in the first year after total gastrectomy for early gastric cancer, the possibility of weight regain is only 19.69–40.67% regardless of the blood data, which is rather low. Such result of nomogram could be an important basis that a multidisciplinary effort for weight recovery is mandatory.
Our work had a few limitations. First, the study was retrospective, performed in a single institution, and included only Asians. Western gastric cancer patients differ; many are obese, have severe disease, and undergo preoperative adjuvant therapy. Therefore, care should be taken when generalizing the results. Second, our predictive malnutrition-risk model has not been externally validated to confirm its accuracy. However, as internal validation was good, the clinical relevance of our model is clear.
In conclusion, we developed and validated a nomogram to predict weight change after gastrectomy for gastric cancer. We studied the body weights and clinicopathological features of a large cohort at various times. We constructed an online weight-prediction model based on a nomogram. This will help clinicians to derive weight patterns easily and efficiently, facilitating nutritional education and medical support. Our tool identifies patients at high risk for failure to maintain appropriate weight after gastrectomy. Such patients require comprehensive support.