Conformal photon-beam radiotherapy of prostate carcinoma

Does the radiation approach affect acute toxicity in prostate cancer patients? A comparison of four radiation techniques

Introduction

Prostate cancer is treated with increasingly sophisticated radiation techniques. The aim of the study is to compare acute toxicity in patients managed with different therapeutic modalities.

Material and methods

A total of 60 patients irradiated between 2012 and 2016 were analyzed: A. conformal 3D - 11, B. intensity-modulated radiation therapy (IMRT) 20, C. image-guided radiation therapy (IGRT) - 19 and D. volumetric modulated arc therapy (VMAT) - 10. Patients' age ranged from 46 to 85 years (median 70.5), prostate-specific antigen values at the time of diagnosis were in the range of 3.54-154 ng/ml (median 15.9). Acute toxicity from the genitourinary (GU) and gastrointestinal (GI) tracts according to the European Organization for Research and Treatment of Cancer (EORTC) /Radiation Therapy Oncology Group (RTOG) grading system were assessed.

Results

All irradiation techniques were well tolerated and neither 3 nor 4 degrees acute toxicity was observed. Importantly, IGRT and IMRT did not lead to Grade 2 GI acute toxicity. There was no relationship between the severity of GU acute toxicity depending on the irradiation technique used (p = 0.8), but a trend towards a significant relationship was noted for GI acute toxicity (p = 0.05).

Conclusions

All assessed irradiation methods do not lead to severe acute adverse effects. Importantly, patients treated with IGRT and IMRT had only minor GI toxicity.

The comparison of 5-field conformal radiotherapy techniques for the treatment of prostate cancer: The best for femoral head sparing

External radiotherapy is a standard treatment procedure for localized prostate cancer. Given the relatively high long term survival treatment complications have been brought in center of attention. In this planning study, between 2012 and 2014, CT simulation data of 90 consecutive high-risk prostate cancer patients were collected. In the first phase, all were planned for whole pelvis irradiation up to 46Gy in 23 daily fractions. In the second phase, only the prostate gland was the target of radiation. Next, the subjects were divided randomly into three groups and each received a unique 5field conformal radiation plan including Plan A (Gantry angle: 0, 60, 120, 240, and 300), Plan B (Gantry angles: 0, 90, 120, 240, and 270) and Plan C (Gantry angles: 0, 60, 90, 270, and 300). The total dose was 70Gy. For each patient, the rectum, bladder, and both femoral heads were contoured as the at risk organs (OAR). From dose volume histograms, the proportional dose of PTV V100, the bladder and rectum V80 and V90 and femoral head V50 and V100 were calculated in all subjects and compared across plans. A statistically significant difference in the femoral head V50 and V100 was found between our studied 5field plans so that in Plan A (beam angles: 0, 60, 120, 240 and 300) less dose was received by both heads of femur. This study suggests that 5 field treatment planning including an anterior, two anterior oblique and two posterior oblique portals to be more proper for 3D conformal radiotherapy in order to spare femoral head with acceptable PTV coverage, and bladder and rectal doses.

Parotid gland-sparing 3-dimensional conformal radiotherapy results in less severe dry mouth in nasopharyngeal cancer patients: a dosimetric and clinical comparison with conventional radiotherapy

BACKGROUND AND PURPOSE

This study examined the efficacy of parotid gland sparing of three-dimensional conformal radiotherapy (3DCRT) compared with conventional radiotherapy for NPC patients. Both the dose given to the parotids and clinical assessment of dry mouth were conducted.

MATERIALS AND METHODS

Dry mouth was assessed for 108 patients treated with conventional technique and 72 treated with 3DCRT. Dose analysis was performed in 48 patients of the 3DCRT group. A dose of 70 Gy was given to the midplane in conventional radiotherapy and to 90% isodose volume in 3DCRT. Prognostic factors affecting the severity of dry mouth were analyzed using Generalized Estimating Equation (GEE).

RESULTS

In the 3DCRT group about 50% of the patients' parotid glands received less than 25 Gy. Parallel analysis of dry mouth shows a significant decrease in the incidence of severe xerostomia after 3DCRT. The proportion of patients without dry mouth was also significantly higher in the 3DCRT group than the conventional group at 1-3 years after completion of radiotherapy. Although 3DCRT delivered a higher dose to the tumor, it spared the parotid gland significantly better than the conventional treatment. Late toxicities were mostly similar between the 2 groups while local control in T4 patients and survival were improved for 3DCRT.

CONCLUSION

Dosimetrically and clinically 3DCRT is better than conventional technique regarding parotid gland protection.