Neoadjuvant chemoradiotherapy is the standard treatment for locally advanced rectal cancer. Fudan University Shanghai Cancer Center has carried out multiple series of studies to explore the optimization of the neoadjuvant therapy since 2005. On the one hand, the "addition" method refers to a higher intensity treatment at the neoadjuvant stage to obtain better tumor regression. On the other hand, the "subtraction" method reduces some unnecessary treatment from the current triad of surgery, radiotherapy and chemotherapy to improve the quality of life of patients. However, locally advanced rectal cancer is associated with great heterogeneity, and therefore, any single treatment mode will not be optimal for all. Notably, the treatment decision-making should be based on clinical presentations, imaging findings, and molecular biology to precisely stratify patients. Besides, the scheme should be dynamically adjusted according to the therapeutic response, so as to realize the dual goals of prolonging patients′ life and improving their quality of life. Meanwhile, the treatment decision-making for target population under the guidance of biomarker should be dynamically and self-adaptively adjusted based on the therapeutic effect. This approach will become the future development direction and objective for the precise medical treatment for rectal cancer.

Objective To determine whether Auto-Planning-based volumetric modulated radiotherapy(Auto-VMAT)planning can improve planning efficiency without compromising plan quality compared with current manual trial-and-error-based volumetric modulated arc therapy(Manual-VMAT) planning for patients with rectal cancer. Methods Ten patients with stage Ⅱ-Ⅲ rectal cancer who underwent Dixon surgery were enrolled as subjects. The Pinnacle 9.10 planning system was used to design Manual-VMAT and Auto-VMAT plans. Dose distribution,homogeneity index(HI),conformity index(CI), D meanvalues of different organs at risk or dose-volume histogram of regions of interest,total planning time, and manual planning time were compared between the two plans. The differences were analyzed by paired t test. Results Dosimetric prescriptions were achieved in both plans. There were no significant differences in HI or CI between the Auto-VMAT plans and the Manual-VMAT plans(0.058 vs. 0.058, P=0.972;0.921 vs. 0.940,P=0.115). Compared with the Manual-VMAT plans,the V 40,D mean,and D 50%of the bladder were significantly reduced by 25.6%, 11.5%, and 8.9%, respectively, in the Auto-VMAT plans(P=0.004,0.016,0.001);the V 40,D mean,and D 50%of the small intestine were also significantly reduced by 12.1%,5.4%,and 6.8%,respectively,in the Auto-VMAT plans(P=0.023,0.001,0.001);the V 30, D mean,and D 50%of the left and right femoral heads were slightly reduced in the Auto-VMAT plans. The Auto-VMAT plans had significantly longer total planning time but significantly shorter manual planning time than the Manual-VMAT plans(50.38 vs. 36.81 min, P= 0.000;4.47 vs. 16.94 min, P= 0.000). Conclusions Compared with the Manual-VMAT plans, the Auto-VMAT plans have substantially shorter manual planning time and improved planning efficiency.