Prostate cancer and carbon ions
With the spread of PSA testing, the number of prostate cancer patients is increasing. Curative treatment for localized prostate cancer is surgery or radiotherapy, with hormone therapy combined depending on the condition. QST Hospital has provided carbon ion therapy since 1994, reducing the number of fractions from 20 (5 weeks) to 16 (4 weeks) and 12 (3 weeks). It has been covered by insurance in Japan since April 2018.
Eligibility criteria
① Cancer must be confirmed by biopsy; cases diagnosed by imaging such as MRI, CT, or PET alone are not eligible. ② It must be localized prostate cancer without metastasis to other organs or lymph nodes.
Cases not eligible
Besides no biopsy or the presence of metastasis, a patient may be ineligible if general condition such as serious complications interferes with treatment or if the physician judges treatment difficult.
Combined hormone therapy
Prostate cancer is classified into low, intermediate, and high risk. For intermediate and high risk, 2–6 months of hormone therapy before carbon ion therapy is recommended, with a recommended total of 6 months for intermediate risk and usually 1–2 years for high risk. Low-risk patients are treated with carbon ions alone without hormone therapy.
Treatment process and schedule
At the first visit, eligibility is assessed using referral documents, and at a second visit about 2 weeks later the risk group and schedule are confirmed. A few months later, at a third visit, a custom immobilization device is made, a planning CT is taken, and consent is obtained (it can be withdrawn after signing). Treatment can be inpatient or outpatient: 12 fractions, 4 per week, about 3 weeks. There is no pain or heat; after about 15 minutes of positioning, irradiation takes 3–4 minutes.
Side effects
During treatment, difficulty urinating or frequent urination is common and usually resolves 1–2 months after treatment. From about 1 year after treatment, bloody stools or blood in the urine may occur, slightly more likely with anticoagulants. Urinary incontinence is rare. With carbon ion therapy alone, sexual function is often preserved, but ejaculatory problems may occur; with combined hormone therapy, hot flashes, reduced muscle strength, and decreased libido may occur.
Clinical trials
Clinical trials of 4 fractions for low and intermediate risk, 4-fraction salvage irradiation for local recurrence after external radiotherapy, and post-treatment quality-of-life surveys have been conducted (as of August 2019).