Effect of 3D-CRT and IMRT on patients with advanced rectal cancer

Objective To investigate the therapeutic effects, complications and dosimetry of different radiotherapy methods in patients with advanced rectal cancer. Methods Eighty-eight patients with advanced rectal cancer who were admitted from May 2014 to May 2017 were divided into intensity modulated radiation therapy(IMRT)group and three-dimentional conformal radiation therapy(3D-CRT)group according to different preoperative radiotherapy methods, with 40 cases in each group.In the IMRT group, there were 25 males and 15 females; the age was(56.2±6.3)years old and the age ranged from 42 to 73 years old.In the 3D-CRT group, there were 23 males and 17 females; the age ranged from(57.5±6.7)years old and the age ranged from 40 to 75 years old.After the postural fixation, CT scan and delineation of the target area, the two groups of patients were performed two different radiotherapy plans, IMRT or 3D-CRT, for radiotherapy.After the therapy, the effects of treatment, adverse reactions, dosimetry, and risk of organ tolerance were observed and compared between the two groups. Results The clinical treatment results of the two groups were compared.The objective response rate of the patients in the IMRT group [70.0%(28/40)] was not significantly different from that in the 3D-CRT group [67.5%(27/40)](P>0.05). There was no significant difference in the adverse reactions of myelosuppression between the two groups after radiotherapy(P>0.05). The incidence of adverse reactions in the digestive system and urinary system in the IMRT group was less than that in the 3D-CRT group(P<0.05). Patients in the IMRT group Dmin [(37.30±1.90)Gy], Dmean[(52.50±0.20)Gy], HI(0.10±0.09), CI(0.70±0.12) were lower than those in the 3D-CRT group [(45.10±2.20)Gy, (53.00±0.30)Gy, (0.30±0.05), (0.90±0.14)], and Dmax [(56.20±0.50)Gy]was higher than[(54.00±0.30)Gy] of the 3D-CRT group(P<0.05). The volume of the bladder(V30)reaching 30 Gy and the bladder volume(V40)reaching 40 Gy in the IMRT group were significantly lower than those in the 3D-CRT group(P<0.05), and in the small intestine, the IMRT group V30 and V40 was lower than those in the 3D-CRT group(P<0.05). Conclusion In the case of the 3D-CRT and IMRT different radiotherapy methods for patients with advanced rectal cancer, the adverse effects caused by IMRT are milder and the degree of organ damage is lower, which is worthy of clinical promotion. Key words: Rectal cancer; Three-dimensional conformal radiotherapy; Intensity modulated radiation therapy; Digestive tract malignancy