The contribution of the cone beam Kv CT (CBKvCT) to the reduction in toxicity of prostate cancer treatment with external 3D radiotherapy

The Usefulness of Adaptative Radiotherapy in Prostate Cancer: How, When, and Who?

The aim of this study was to develop a deformable image registration (DIR)-based offline ART protocol capable of identifying significant dosimetric changes in the first treatment fractions to determine when adaptive replanning is needed. A total of 240 images (24 planning CT (pCT) and 216 kilovoltage cone-beam CT (CBCT)) were prospectively acquired from 24 patients with prostate adenocarcinoma during the first three weeks of their treatment (76 Gy in 38 fractions). This set of images was used to plan a hypofractionated virtual treatment (57.3 Gy in 15 fractions); correlation with the DIR of pCT and each CBCT allowed to translate planned doses to each CBCT, and finally mapped back to the pCT to compare with those actually administered. In 37.5% of patients, doses administered in 50% of the rectum (D50) would have exceeded the dose limitation to 50% of the rectum (R50). We first observed a significant variation of the planned rectal volume in the CBCTs of fractions 1, 3, and 5. Then, we found a significant relationship between the D50 accumulated in fractions 1, 3, and 5 and the lack of compliance with the R50. Finally, we found that a D50 variation rate [100 × (administered D50 − planned D50/planned D50)] > 1% in fraction three can reliably identify variations in administered doses that will lead to exceeding rectal dose constraint.

A Ten-year-long Update on Radiation Proctitis Among Prostate Cancer Patients Treated With Curative External Beam Radiotherapy

This comprehensive synopsis summarizes the most relevant information obtained from a systematic analysis of studies of the last decade on radiation proctitis, one of the most feared radioinduced side effects among prostate cancer patients treated with curative external beam radiotherapy. The present review provides a useful support to radiation oncologists for limiting the onset or improving the treatment of radiation proctitis. This work shows that the past decade was a harbinger of significant new evidence in technological advances and technical tricks to avoid radiation proctitis, in addition to dosimetric perspectives and goals, understanding of pathogenesis, diagnostic work-up and treatment. We believe that a well-rounded knowledge of such an issue is fundamental for its appropriate management.

Modern intensity-modulated radiotherapy with image guidance allows low toxicity rates and good local control in chemoradiotherapy for anal cancer patients

PURPOSE

To report outcomes of a population of anal cancer patients treated with modern intensity-modulated radiotherapy and daily image-guided radiotherapy techniques.

METHODS

We analyzed data of 155 patients consecutively treated with intensity-modulated radiotherapy +/- chemotherapy in three radiotherapy departments. One hundred twenty-two patients presented a stage II-IIIA disease. Chemotherapy was administered in 138 patients, mainly using mitomycin C and 5-fluorouracil (n = 81). All patients received 36 Gy (1.8 Gy/fraction) on the pelvic and inguinal nodes, on the rectum, on the mesorectum and on the anal canal, and a sequential boost up to a total dose of 59.4 Gy (1.8 Gy/fraction) on the anal canal and on the nodal gross tumor volumes.

RESULTS

Median follow-up was 38 months (interquartile range 12-51). Toxicity data were available for 143 patients: 22% of them presented a G3+ acute toxicity, mainly as moist desquamation (n = 25 patients) or diarrhea (n = 10). Three patients presented a late grade 3 gastrointestinal toxicity (anal incontinence). No grade 4 acute or late toxicity was recorded. Patients treated with fixed-gantry IMRT delivered with a sliding window technique presented a significantly higher risk of acute grade 3 (or more) toxicity compared to those treated with VMAT or helical tomotherapy (38.5 vs 15.3%, p = 0.049). Actuarial 4-year local control rate was 82% (95% CI 76-91%).

CONCLUSIONS

Modern intensity-modulated radiotherapy with daily image-guided radiotherapy is effective and safe in treating anal cancer patients and should be considered the standard of care in this clinical setting.

[Partial delegation to radiation therapists of the control by cone beam CT of prostate positioning]

PURPOSE

Intensity modulated radiotherapy for prostate cancer involves daily monitoring of the positioning of the prostate, possible with cone beam CT (CBCT). It allows increased accuracy compared to readjustments but induces an increase in the time dedicated to these medical checks. The aim of the study was to evaluate the possibility of delegation of this task to the radiation therapists by comparing their readjustments to the doctors.

PATIENTS AND METHODS

Five consecutive patients treated with radiation for prostate cancer (76Gy) were analysed. All had a daily CBCT for position control. The movements of the prostate relative to the bony part, the positional variations of the prostate measured by the radiation therapists and the doctors and medical time required to analyse imagery (filling of the rectum and bladder and perform a recalibration) were measured.

RESULTS

One hundred seventy-six CBCT were analysed or 980 steps in the three axes. The movements of the prostate relative to bony part were respectively at least 5mm in 19%, 7% and 3% in the anterior-posterior, upper-lower and right-left axes. Changes readjustments between radiation therapists and doctors were in 95% of cases at the most 4mm in the anterior-posterior and upper-lower axis, and 3mm in the left-right axis. The time for medical use of the CBCT averaged 8min 40 [4 to 22min].

CONCLUSION

The daily readjustment on the prostate using CBCT may be delegated to radiation therapists with acceptable concordance of less than 4mm for 95% of measurements. An initial and ongoing training will ensure treatment safety.

Ethnic Difference in Risk of Toxicity in Prostate Cancer Patients Treated with Dynamic Arc Radiation Therapy

Aims and background

The objective of this study was to assess the influence of ethnicity on toxicity in patients treated with dynamic arc radiation therapy (ART) for prostate cancer (PC).

Methods

From June 2006 to May 2012, 162 cT1-T3 cN0 cM0 PC patients were treated with ART (primary diagnosis, n = 125; post-prostatectomy/brachytherapy biochemical recurrence, n = 26; adjuvant post-prostatectomy, n = 11) at 2 institutions. Forty-five patients were Latin Americans and 117 were Europeans. The dose prescribed to the prostate ranged between 68 Gy and 81 Gy.

Results

The median age was 69 years (range 43-87 years). The median follow-up was 18 months (range 2-74 months). Overall, only 3 patients died, none due to a cancer-related cause. Biochemical recurrence was seen in 7 patients. The rates of acute grade 2 gastrointestinal (GI) and genitourinary (GU) toxicities were 19.7% and 17%, respectively. Only 1 patient experienced acute grade 3 GI toxicity, whereas 11 patients (6.7%) experienced acute grade 3 GU toxicity. Multivariate analysis showed that undergoing whole pelvic lymph node irradiation was associated with a higher grade of acute GI toxicity (OR: 3.46; p = 0.003). In addition, older age was marginally associated with a higher grade of acute GI toxicity (OR: 2.10; p = 0.074). Finally, ethnicity was associated with acute GU toxicity: Europeans had lower-grade toxicity (OR: 0.27; p = 0.001).

Conclusions

Our findings suggest an ethnic difference in GU toxicity for PC patients treated with ART. In addition, we found that ART is associated with a very low risk of severe toxicity and a low recurrence rate.