Particle beam radiation therapy in prostate cancer: is there an advantage?

Carbon ion irradiation of the human prostate cancer cell line PC3: a whole genome microarray study

Hadrontherapy is a form of external radiation therapy, which uses beams of charged particles such as carbon ions. Compared to conventional radiotherapy with photons, the main advantage of carbon ion therapy is the precise dose localization along with an increased biological effectiveness. The first results obtained from prostate cancer patients treated with carbon ion therapy showed good local tumor control and survival rates. In view of this advanced treatment modality we investigated the effects of irradiation with different beam qualities on gene expression changes in the PC3 prostate adenocarcinoma cell line. For this purpose, PC3 cells were irradiated with various doses (0.0, 0.5 and 2.0 Gy) of carbon ions (LET=33.7 keV/μm) at the beam of the Grand Accélérateur National d’Ions Lourds (Caen, France). Comparative experiments with X-rays were performed at the Belgian Nuclear Research Centre. Genome-wide gene expression was analyzed using microarrays. Our results show a downregulation in many genes involved in cell cycle and cell organization processes after 2.0 Gy irradiation. This effect was more pronounced after carbon ion irradiation compared with X-rays. Furthermore, we found a significant downregulation of many genes related to cell motility. Several of these changes were confirmed using qPCR. In addition, recurrence-free survival analysis of prostate cancer patients based on one of these motility genes (FN1) revealed that patients with low expression levels had a prolonged recurrence-free survival time, indicating that this gene may be a potential prognostic biomarker for prostate cancer. Understanding how different radiation qualities affect the cellular behavior of prostate cancer cells is important to improve the clinical outcome of cancer radiation therapy.

Approaches to the prevention and management of radiation colitis

Radiation colitis refers to the characteristic changes in the mucosa of the colon and rectum secondary to pelvic radiation. Based on the interval from radiation to mucosal changes or symptoms, there are two well-defined forms of radiation colitis: acute, manifested by mucosal sloughing causing diarrhea, mucus discharge, and tenesmus; and chronic, characterized by obstructed defecation or ischemia of the mucosa due to obliterative endarteritis and resulting in mucosal telangiectasias, mucosal pallor, and friability causing rectal bleeding. Up to 25% of all patients receiving pelvic radiation develop mild symptoms, and 2% to 3% develop moderate to severe symptoms. Radiation colitis can be difficult to treat in some patients. There are several options for treating its symptoms. Argon plasma coagulation is the most common method of treating telangiectasias. Topical formaldehyde has also been used for distal telangiectasias. Obstructed defecation caused by radiation strictures (which are very fibrotic) usually can be treated successfully with stool softeners, colonic dilation, or steroid injection. Surgery should be avoided if possible because of its technical difficulty and the high incidence of postoperative complications such as anastomotic leak and fistula formation. New advances in radiation delivery techniques (eg, intensity-modulated radiation therapy) using specialized computer algorithms and medications such as amifostine may decrease the incidence of radiation colitis.

Clinical and research validity of hadrontherapy with ion beams

Clinical results obtained with hadrontherapy have been extremely positive for various tumours, with percentages of local control and survival higher than those ascribed to conventional radiotherapy. Most clinical data obtained with charged particles are related to protontherapy but the implementation of carbon ion therapy has demonstrated to be of great interest in the last decade. These results, accompanied by the new performances in accelerator technology and calculation systems of the delivered doses, have determined over the past years an increased interest for the development of hadrontherapy, with the construction of new centres provided with equipment entirely dedicated to clinical activity (LLUMC, Loma Linda and NPTC, Boston in USA, HIMAC-NIRS, Chiba, PROBEAT, Tsukuba, and Hyogo Beam Medical Centres in Japan). A revision of the clinical indications specifically focused on ion therapy is presented as well as the results obtained in the different centres. With hadrontherapy, it is finally possible to increase the spectrum of treatments allowing preserving the organ and its functionality, with positive impacts from a social and economic point of view.

High-dose-rate brachytherapy in the treatment of carcinoma of the prostate

BACKGROUND

Although radical prostatectomy for localized disease is considered as a standard of care, external-beam radiotherapy and brachytherapy are equally effective. We report on the technique and preliminary results of high-dose-rate (HDR) brachytherapy using a temporary iridium-192 implant technique.

METHODS

The authors reviewed the literature on the techniques, treatment protocols, and results of HDR brachytherapy in the treatment of carcinoma of the prostate, and they report their own protocols, technique, and results.

RESULTS

The combination of HDR brachytherapy and external irradiation has been well tolerated by all 200 patients in our series, with less than 3% grade 3 late complications and with 95% PSA relapse-free survival with a median follow-up of 24 months.

CONCLUSIONS

HDR brachytherapy may be the most conformal type of irradiation in the treatment of carcinoma of the prostate regardless of tumor size, anatomical distortion, and organ mobility.

The treatment of prostate cancer: an overview of current options

PURPOSE

The purpose of this report is to discuss the current treatment options available to the patient with prostate cancer in all stages of the disease.

OVERVIEW

With the exception of skin cancer, prostate cancer is the most common cancer in men in the United States. Most patients in the current era will present with organ-confined disease, amenable to curative treatment. Treatment for organ-confined disease includes watchful waiting, radical prostatectomy, radiation therapy, and cryosurgery in selective cases. Hormone therapy is the cornerstone of treatment of patients with advanced prostate cancer. There is no curative treatment for hormone-refractory prostate cancer.

CLINICAL IMPLICATIONS

The availability of several therapeutic options for localized prostate cancer warrants careful consideration when planning treatment with curative intent. Patients need to be active participants in decision making, and they must be aware of the benefits and possible complications of the different types of treatment. Patients with advanced prostate cancer need to be aware that hormone treatment will provide temporization and palliation in the majority of cases. Hormone-resistant prostate cancer is refractory to most forms of conventional and experimental therapy.

Conformal proton therapy for early-stage prostate cancer

OBJECTIVES

To assess the effect of proton radiation on clinical and biochemical outcomes for early prostate cancer.

METHODS

Three hundred nineteen patients with T1-T2b prostate cancer and initial prostate-specific antigen (PSA) levels 15.0 ng/mL or less received conformal radiation doses of 74 to 75 cobalt gray equivalent with protons alone or combined with photons. No patient had pre- or post-treatment hormonal therapy until disease progression was documented. Patients were evaluated for biochemical disease-free survival, PSA nadir, and toxicity; the mean and median follow-up period was 43 months.

RESULTS

Overall 5-year clinical and biochemical disease-free survival rates were 97% and 88%, respectively. Initial PSA level, stage, and post-treatment PSA nadir were independent prognostic variables for biochemical disease-free survival: a PSA nadir 0.5 ng/mL or less was associated with a 5-year biochemical disease-free survival rate of 98%, versus 88% and 42% for nadirs 0.51 to 1.0 and greater than 1.0 ng/mL, respectively. No severe treatment-related morbidity was seen.

CONCLUSIONS

It appears that patients treated with conformal protons have 5-year biochemical disease-free survival rates comparable to those who undergo radical prostatectomy, and display no significant toxicity. A Phase III randomized dose-escalation trial is underway to define the optimum radiation dose for early-stage prostate cancer.