This study assessed whether the existing MDT discussion mode could bring survival benefits to patients with metastatic gastrointestinal cancer. Based on the requirements of ethics, it is difficult to design and carry out a randomized controlled study to answer this question directly. Therefore, the patients were categorized based on the implementation of the MDT discussion to evaluate the difference in OS, hoping to give an indirect answer. This was a major limitation of this study.
This study showed that the OS of patients was significantly longer in the implementation group than in the nonimplementation group, suggesting that the current MDT discussion played a positive role in patients with metastatic gastrointestinal cancer. This was the first prospective controlled study to try to answer this question. However, being a noninterventional study, selection bias might exist in patient selection. Although nearly 500 patients were included in the study, only 66 were in the nonimplementation group at the time of discontinuation of enrolment. The expected number of patients to be enrolled was not reached, and, therefore, the statistical comparison efficiency might decline. In addition, the study included as many factors as possible that might affect survival; however, still some features were not listed, such as specific issues discussed and specific location and number of tumours, thus increasing the probability of false-positive results.
In the subgroup analysis, the results showed that the survival benefit of patients with colorectal cancer who implemented MDT decisions was more obvious. Previous studies showed that in metastatic colorectal cancer, especially liver metastasis or lung metastasis, multidisciplinary treatment could significantly prolong survival[7, 8], and this concept has been widely used in clinical practice. The results of the subgroup analysis of colorectal cancer in the present study showed that the analysis data were consistent with previous clinical findings[9, 10]. More importantly, most patients with advanced colorectal cancer, whether they accepted MDT decisions, would still receive multidisciplinary comprehensive treatment in clinical practice. Therefore, the results of this study suggested that formal MDT discussion was still necessary for these patients.
In the subgroup analysis of gastric cancer, patients with MDT decision-making did not have significant survival benefits, which might be associated with the characteristics of metastatic gastric cancer. MDT of metastatic gastric cancer mainly focuses on retroperitoneal lymph node dissection, liver metastasis resection, hyperthermic intraperitoneal chemotherapy, and resection of Krukenberg’s tumor. However, whether the application of these treatments can prolong the survival of patients with metastatic gastric cancer is controversial[12, 13]. Although some treatment methods could not prolong the survival, systematic treatment combined with local treatment might improve the quality of life of patients with obstruction, perforation, bleeding, or pain. Unfortunately, the quality of life was not evaluated in this study, which was another limitation of this study.
The implementation rate of MDT decision in this study was similar to that reported in the past (80–90%), indicating the trust of patients in MDT decision-making. The patient's background and disease characteristics were recorded, hoping to identify the main reasons associated with the refusal of MDT decision. This study showed that female patients had better compliance, which might be related to Chinese traditional culture. At the same time, patients who had not received previous treatment were more likely to refuse to implement MDT decisions than those who had received at least two-line treatment. This was a matter of caution because MDT decision-making might be more important for patients with newly diagnosed advanced cancer. Another important factor in not implementing MDT decision was the change in patient's condition in a later stage. Strictly speaking, this was not the patient's subjective intention to refuse to accept the original MDT decision. The present study found that almost all of the patients who failed to continue MDT decisions due to changes in their condition were not scheduled to receive another MDT discussion. This finding suggested that MDT discussion should be used not only in the initial treatment decision but also throughout the management of patient treatment. In addition, nearly half of the patients were not willing to talk about the reasons for denying the implementation of MDT decision. In general, patients were not invited to participate in MDT discussions. Hence, doctors might ignore patients' thoughts and concerns in MDT decision-making, affecting the acceptance and implementation of MDT decisions.
This study aimed to analyze what the best MDT mode was. The results showed that the participation of three to five disciplines and 15–20 mins of discussion time were suitable for completing MDT discussion in each case. Patients with colorectal cancer and patients who had not received previous treatment might benefit more from MDT discussion. An interesting phenomenon in the study was that most of the doctors who made the final MDT decision after discussion were oncologists. This might be related to the fact that all the participants involved in the discussion were patients with advanced cancer; oncologists need to focus more on the treatment process.
To sum up, despite limitations, the results of this study showed that the formal MDT discussions could significantly prolong the survival of patients with metastatic gastrointestinal cancer, especially for patients with metastatic colorectal cancer. At the same time, when the condition changes, it is necessary to schedule the next MDT discussion in time.