Is radiotherapy and chemotherapy necessary before and after radical surgery for gastric cancer? How to evaluate?

Author: Liang Bin, Chief Physician, Peking University People's Hospital

Reviewer: Yu Yanyan, Chief Physician, Peking University First Hospital

The mainstream surgical method for gastric cancer is radical surgery. Depending on the location and size of the tumor, partial gastrectomy or total gastrectomy, including peripheral lymph node dissection, can be performed. The standard for radical surgery is that no residual lesions can be seen under the naked eye or microscope. Radical surgery can be performed for early gastric cancer or locally advanced gastric cancer without distant metastasis.

Before radical surgery for gastric cancer, first of all, oncological evaluation, histopathological diagnosis, and imaging examination for staging are required; secondly, the patient's physical tolerance should be evaluated, including cardiopulmonary function, liver and kidney function, etc., to determine whether the patient can tolerate radical surgery. In addition, it is also necessary to evaluate whether radiotherapy and chemotherapy are needed before and after radical surgery.

Early-stage gastric cancer generally does not require preoperative radiotherapy or chemotherapy. For digestive tract tumors, radiotherapy is a very effective treatment in some cases. If the target area of ​​radiotherapy moves, the effect of radiotherapy will be affected, and other organs may be irradiated, and side effects or damage will be relatively increased. Therefore, the target organ or target site of radiotherapy must be relatively fixed in order to achieve relatively good results. For example, proximal gastric cancer, or gastric cancer near the cardia, is relatively fixed in position and is located at the junction of the stomach and esophagus. For advanced proximal gastric cancer, if surgery cannot guarantee a radical effect, a treatment strategy combining preoperative radiotherapy and chemotherapy can be considered.

At present, most people believe that if the gastric cancer stage is within the T3+N+ stage range, preoperative neoadjuvant chemotherapy is recommended. Clinical studies have shown that the overall survival of these patients has improved after neoadjuvant chemotherapy.

Preoperative neoadjuvant chemotherapy can, first of all, remove some tiny metastatic lesions, because some tiny metastatic lesions cannot be seen in imaging; secondly, chemotherapy can downgrade the stage of the disease. For example, if the disease was originally in stage T3N3, it may be downgraded to stage T2N2 after chemotherapy, which will reduce the difficulty of surgery and may improve the long-term effect; thirdly, chemotherapy can help us understand which chemotherapy drugs the patient is more sensitive to; fourthly, the patient's digestive tract anatomy is normal before surgery, and his tolerance to chemotherapy is better than that after surgery, and the side effects are also smaller than after surgery.

Figure 1 Original copyright image, no permission to reprint

Generally, 4-6 courses of chemotherapy are required before radical surgery for gastric cancer. Clinical studies have shown that with such a long chemotherapy, the overall clinical response of patients is relatively good. Domestic studies have shown that the tumor control rate is basically between 60% and 80%, which means that most patients do not show any progression. If more chemotherapy courses are added, a greater downstaging effect cannot be achieved, the patient's tolerance will decrease, and the tolerance to surgery will also become relatively worse, and a better treatment effect cannot be achieved. Regular evaluation is required during the preoperative neoadjuvant chemotherapy period. Generally, an imaging evaluation is performed after 2-3 courses of chemotherapy. Based on the response of the lesion site, it is determined whether the chemotherapy regimen needs to be revised. With conventional chemotherapy drugs, surgery can generally be performed 2 weeks after the end of chemotherapy.

The definition of radical surgery is that there is no tumor residue visible to the naked eye or under the microscope. However, it is currently impossible to detect whether there are tiny hidden tumor cells in the body.

After radical surgery, the tissue specimens removed must be pathologically staged. If the pathological examination indicates early gastric cancer and there is no lymph node metastasis, postoperative adjuvant chemotherapy may not be performed. If the tumor is in the advanced stage, especially in patients with lymph node metastasis, the possibility of residual occult micro-tumor lesions after surgery will increase. For this reason, postoperative adjuvant chemotherapy is used to eliminate tumor cells that may be free in various parts of the body. Clinical studies have shown that for advanced gastric cancer, postoperative chemotherapy can significantly improve the patient's 5-year survival rate.

Figure 2 Original copyright image, no permission to reprint

If the patient has not received chemotherapy before surgery, and postoperative pathological evaluation shows that adjuvant chemotherapy is needed, 6-8 courses of treatment are usually required, with each course lasting 21 days. If the patient has received neoadjuvant chemotherapy before surgery and the chemotherapy effect is significant, but there is still residual tumor after surgery, chemotherapy may need to continue according to the original plan until about 8 courses of chemotherapy are completed. If there are no tumor cells remaining in the resected specimen, subsequent adjuvant chemotherapy can be discontinued, or 4 more courses of consolidation can be performed according to the preoperative chemotherapy plan. If the preoperative chemotherapy is not effective, the chemotherapy plan needs to be changed, and the treatment should be carried out according to the course specified in the new plan.