Study On Application Of Adaptive Radiotherapy (ART) Plan During External Radiotherapy Course For Locally Advanced Cervical Cancer And Observations Of The Clinical Effects

Objective The paper was to study radiated volume and characteristics of dosage change in targeted region and organ, which was treated with external radiation for locally advanced cervical cancer with single off-line adaptive intensity modulated radiation therapy; preliminary clinical effect and toxic and side effect differences were compared in different external radiotherapy modes for locally advanced cervical cancer, which adopt strategy of singe off-line adaptive intensity modulated radiotherapy or the strategy of single-course intensity modulated radiotherapy, therefore, to explore proper treatment mode.Material and Method 1. A total of 112 locally advanced cervical cancer cases(Stage IIB-IVA) who received concurrent radiochemotherapy in our hospital from May 2010 to May 2015 were enrolled and divided into two groups according to their external irradiation mode, including(1)the single-course radiotherapy group(n=62), whose radiotherapy plan remained unchanged during the whole course of external radiotherapy, and(2)the single off-line adaptive radiotherapy group(ART Group; n=50), who received 15 external radiation(27Gy) according to original plan(Plan1), were rescanned then for the design of off-line adaptive plan(Plan2) according to same prescribed dosage and restriction standards, and received 10 subsequent treatments on the basis of new plan. IMRT or IGRT technology was adopted for external radiation in both groups; prescribed dosage was 1.8-2.0Gy/f*23-25 f for both groups; IMRT synchronized dosage compensation 3D-ICBT with high dosage rate was adopted for intracavitary therapy; Cis-platinum was the basic medication for synchronized chemotherapy regimens. 2. For the first stage, radiotherapy regimens of two stages in the ATR Group were compared to determine volume and dosage change characteristics of region targeted and organ involved in off-line adaptive radiotherapy after 15 times of external irradiation. 3. For the second stage, patients were followed up by regular outpatient reexaminations,telephone interviews and other modes to evaluate survival conditions and occurrences of toxic and side effects in patients. Survival rates as well as differences of acute and chronic toxic and side effect occurrence rate were compared between the two groups.Result 1. The followings were shown the related dosimetric study in the ART Group.(1) Average GTV volume was decreased for(41.12±13.02)cm3 from(107.67±32.02)cm3 before treatment to(63.21±25.78)cm3 after 15 times of irradiation with an average reduction rate of(35.48±5.16) %(p < 0.05);Average p CTV volume was decreased for( 36.84+7.96) cm3 from319.86±25.96) cm3 before treatment to(285.02±19.26)cm3 after 15 times of irradiation with an average reduction rate of( 9.53±1.90) %(p < 0.05);Statistical significances were shown in both aspects. Changes of rectum,bladder and small intestine volumes showed no statistical difference between two plans.(2) In off-line adaptive radiotherapy regimes after radiotherapy with15 f, p GTV D95 dosage showed an increasing trend(46.14±0.77 Gy VS46.31±0.25 Gy for Plan1 and Plan2 respectively, p>0.05), yet the difference was not significant. It was shown by comparison involved organ DVH parameters that For involved organs, rectum Dmax, Dmean, D0.1cc and D1 cc,small intestinal Dmean, Dmax, V30,V45 and V50, and bladder Dmax, Dmean,D0.1cc and D1 cc after Plan 2 all decreased than after Plan 1. Among them,decreases of rectum Dmax(52.05±0.77 Gy VS 50.15±0.69 Gy, p=0.03),Dmean(37.09±0.74 Gy VS 34.18±0.99 Gy, p=0.011), D 0.1cc( 51.60±5.39 Gy VS 49.17±2.22 Gy,p=0.025),D 1cc( 49.90±4.19 Gy VS 48.21±2.02 Gy,p=0.045)and Bladder Dmean(35.36±0.54 Gy VS 34.46±0.50 Gy, p=0.023),Dmax(54.88±0.89 Gy VS 52.53±1.19 Gy, p=0.028), D 0.1cc( 53.82±5.20 Gy VS 51.72±3.54 Gy,p=0.041)、D 1cc( 52.61±4.64 Gy VS 50.60±3.28 Gy,p=0.021)were all statistically significant, indicating that 15-times off-line adaptive plan reduced exposure doses of rectum and bladder to different extents.2. It was indicated by survival analysis in two groups that the 3-year OS(p>0.05) and PFS(p>0.05) were 95.2% and 93.3% in the ART Group and90.9% and 80.4% in the single-course radiotherapy group; the intergroup difference showed no statistical significance. CTCAE V4.0 was referred for evaluation of acute and chronic toxic and side effects. Occurrence rate of acute diarrhea in the single-course radiotherapy group was significantly higher than the ART Group(48.39% VS 30%, p=0.046). While occurrence rates of other chronic and acute toxic and side effects showed no significant differences between the two groups.Conclusion 1. Updates of radiotherapy regimes during external irradiation for locally advanced cervical cancer reduced irradiated dosages in rectum and bladder, positively protecting involved organs; 2. External irradiations for locally advanced cervical cancer with single off-line intensity-modulated adaptive radiotherapy and with single-course intensity-modulated radiation therapy showed no significant difference on 3-year OS and PFS. Both therapy modes carried favorable therapeutic effects. 3. Implementation of adaptive therapy during radiotherapies might reduce occurrence some acute diarrhea of radiotherapy in patients and improved patient tolerance during treatments, yet further studies are required.