Prostate Cancer Radiotherapy: An Evolving Paradigm

Prostate radiotherapy and the risk of secondary rectal cancer-a meta-analysis

PURPOSE

Radiotherapy is being used increasingly in the treatment of prostate cancer. However, ionising radiation may confer a small risk of a radiation-induced secondary malignancy. We aim to assess the risk of rectal cancer following pelvic radiotherapy for prostate cancer.

METHODS

A search was conducted of the PubMed/MEDLINE, EMBASE and Web of Science databases identifying studies reporting on the risk of rectal cancer following prostatic radiotherapy. Studies must have included an appropriate control group of non-irradiated prostate cancer patients. A meta-analysis was performed to assess the risk of prostatic radiotherapy on subsequent rectal cancer diagnosis.

RESULTS

In total, 4757 articles were screened with eight studies meeting the predetermined criteria. A total of 796,386 patients were included in this meta-analysis which showed an increased odds ratio (OR) for subsequent rectal cancer in prostate cancer patients treated with radiotherapy compared to those treated by non-radiotherapy means (OR 1.45, 1.07-1.97, p = 0.02).

CONCLUSION

These findings confirm that prostate radiotherapy significantly increases the risk of subsequent rectal cancer. This risk has implications for treatment selection, surveillance and patient counselling. However, it is crucial that this information is presented in a rational and comprehensible manner that does not disproportionately frighten or deter patients from what might be their most suitable treatment modality.

Population-Level Uptake of Moderately Hypofractionated Definitive Radiation Therapy in the Treatment of Prostate Cancer

PURPOSE

Recent evidence shows the noninferiority of hypofractionated radiation therapy regimens compared with conventional regimens in the treatment of prostate cancer (PCa). Hypofractionation has benefits for both the patient and health care system, because of the shorter treatment duration. Despite this advantage, the uptake of hypofractionation can be slow. Here we investigate the factors influencing the changing use of moderate hypofractionation (HypoRT) for the treatment of PCa.

METHODS AND MATERIALS

We conducted a population-based, retrospective, consecutive cohort study using the 2014 to 2018 Outpatient Radiation Oncology Data from public and private treatment facilities in New South Wales, Australia. Included participants had a PCa diagnosis of any risk, and they completed curative-intent external beam radiation therapy without treatment to lymph nodes. Factors potentially affecting use of HypoRT were examined using a 3-level hierarchical logistic regression model. The effects were reported using adjusted, median, or interval odds ratios.

RESULTS

The study included 4915 patients. Of these, 4053 patients (82.5%) received conventional fractionation, and 862 patients (17.5%) received HypoRT. HypoRT utilization increased from 5.2% in 2014 to 40.3% in 2018. The treating radiation oncologist, treatment facility, and increasing distance to treatment centers had the greatest influence on HypoRT uptake. The main limitation was the lack of stratification by PCa risk categorization.

CONCLUSIONS

Although HypoRT uptake has considerably increased between 2014 and 2018, it remains variable among facilities and treating radiation oncologists. Strategies are being explored to reduce inter-clinician variability.

Prognostic value of microRNA-20b expression level in patients with prostate cancer

BACKGROUND

miR-20b is a member of the miR-106a-363 gene cluster located in the mammalian X chromosome, the larger miR-17 family, and the miR-17-92 and miR-106b-25 gene clusters. Previous studies have indicated that miR-20b may function as oncogene or tumor suppressor in different types of cancers. The present study analyzed the association between miR-20b and clinicopathological characteristics of patients with prostate cancer.

METHODS

A total of 127 pairs of prostate cancer tissue samples and adjacent prostate tissue samples were collected from April 2013 to March 2018. The associations between miR-20b expression levels and clinicopathological factors were assessed using the χ2‑test. Survival was estimated using the Kaplan-Meier method, and the differences in survival according to miR-20b expression were compared using the log-rank test. Prognostic values of miR-20b expression and clinical outcomes were evaluated by Cox regression analysis.

RESULTS

The relative expression of miR-20b in prostate cancer tissues was significantly higher than that in adjacent noncancerous prostate tissues (P<0.001). miR-20b expression was observed to be significantly associated with Gleason score (P<0.001), lymph node metastasis (P<0.001), and TNM stage (P=0.002). The log-rank test indicated that patients with increased miR-20b expression experienced poor overall survival (P=0.037). Multivariate Cox regression analysis showed that miR-20b expression level (HR=2.181, 95% CI: 1.772-9.021, P=0.016) was an independent factor in predicting the overall survival of prostate cancer patients.

CONCLUSION

The present study demonstrated that tissue miR-20b expression level could be a promising biomarker of prognosis in prostate cancer.

Real-Time Image Guided Ablative Prostate Cancer Radiation Therapy: Results From the TROG 15.01 SPARK Trial

PURPOSE

Kilovoltage intrafraction monitoring (KIM) is a novel software platform implemented on standard radiation therapy systems and enabling real-time image guided radiation therapy (IGRT). In a multi-institutional prospective trial, we investigated whether real-time IGRT improved the accuracy of the dose patients with prostate cancer received during radiation therapy.

METHODS AND MATERIALS

Forty-eight patients with prostate cancer were treated with KIM-guided SABR with 36.25 Gy in 5 fractions. During KIM-guided treatment, the prostate motion was corrected for by either beam gating with couch shifts or multileaf collimator tracking. A dose reconstruction method was used to evaluate the dose delivered to the target and organs at risk with and without real-time IGRT. Primary outcome was the effect of real-time IGRT on dose distributions. Secondary outcomes included patient-reported outcomes and toxicity.

RESULTS

Motion correction occurred in ≥1 treatment for 88% of patients (42 of 48) and 51% of treatments (121 of 235). With real-time IGRT, no treatments had prostate clinical target volume (CTV) D98% dose 5% less than planned. Without real-time IGRT, 13 treatments (5.5%) had prostate CTV D98% doses 5% less than planned. The prostate CTV D98% dose with real-time IGRT was closer to the plan by an average of 1.0% (range, -2.8% to 20.3%). Patient outcomes showed no change in the 12-month patient-reported outcomes compared with baseline and no grade ≥3 genitourinary or gastrointestinal toxicities.

CONCLUSIONS

Real-time IGRT is clinically effective for prostate cancer SABR.

Biochemical relapse free survival rate in patients with prostate cancer treated with external radiotherapy: outcomes obtained at the CMN Siglo XXI Hospital de Oncología, CMN 20 de Noviembre and Hospital General de México of the México City

Aim

Biochemical relapse-free survival (bRFS) rate is determined by a cohort of Mexican patients (n = 595) with prostate cancer who received treatment with external radiotherapy.

Background

Patients with prostate cancer were collected from CMN Siglo XXI (IMSS), CMN 20 de Noviembre (ISSSTE), and Hospital General de México (HGM). For the IMSS, 173 patients that are treated with three-dimensional conformal radiation therapy (3D-CRT) and 250 with SBRT, for the ISSSTE 57 patients are treated with 3D-CRT and on the HGM 115 patients are managed with intensity modulated radiation therapy (IMRT). The percentage of patients by risk group is: low 11.1%, intermediate 35.1% and high 53.8%. The average follow-up is 39 months, and the Phoenix criterion was used to determine the bRFS.

Materials and methods

The Kaplan-Meier technique for the construction of the survival curves and, the Cox proportional hazards to model the cofactors.

Results

(a) The bRFS rates obtained are 95.9% for the SBRT (7 Gy fx, IMSS), 94.6% for the 3D-CRT (1.8 Gy fx, IMSS), 91.3% to the 3D-CRT (2.65 Gy fx, IMSS), 89.1% for the SBRT (7.25 Gy fx, IMSS), 88.7% for the IMRT (1.8 Gy fx, HGM) %, and 87.7% for the 3D-CRT (1.8 Gy fx, ISSSTE). (b) There is no statistically significant difference in the bRFS rates by fractionation scheme, c) Although the numerical difference in the bRFS rate per risk group is 95.5%, 93.8% and 89.1% for low, intermediate and high risk, respectively, these are not statistically significant.

Conclusions

The RT techniques for the treatment of PCa are statistically equivalent with respect to the bRFS rate. This paper confirms that the bRFS rates of Mexican PCa patients who were treated with conventional vs. hypofractionated schemes do not differ significantly.