Treatment options for renal cell carcinoma
Surgery is the first-line treatment for the primary tumor. When surgery is difficult, ablation such as cryotherapy or radiofrequency ablation is used, usually for small tumors up to about 3 cm. If that is also difficult, systemic therapy such as molecular targeted drugs is considered.
Radiotherapy and carbon ion therapy
Because normal kidney tissue is sensitive to radiation and renal cell carcinoma was considered poorly responsive to it, radiotherapy was rarely used in the past. Carbon ion beams combine a physical property that allows irradiation limited to the tumor and its surroundings with a strong cell-killing biological property, so they are considered a suitable form of radiotherapy for renal cell carcinoma.
Category in Japan and number of fractions
Treatment with 12 fractions (about 3 weeks) is provided as Advanced Medical Care. A clinical trial was also conducted to confirm the safety and effectiveness of 4 fractions (4 days to 1 week) in some eligible patients (as of August 2019).
Eligibility criteria
① Renal cell carcinoma must be confirmed by biopsy or imaging. ② Localized renal cell carcinoma is eligible; even with metastasis, a patient may be eligible depending on general condition.
Cases that are difficult to treat
If the tumor is close to the bowel, the area in contact with the bowel cannot receive a sufficient dose (risk of serious complications such as perforation), making treatment difficult. A patient may also be ineligible if serious complications or general condition interfere with treatment, or if the physician judges treatment difficult.
Treatment process
At the first visit, eligibility is assessed using documents from the referring hospital. Then, as a rule, the patient is admitted for imaging, metal markers for position verification are placed in the kidney tissue around the tumor, a custom immobilization device is made, and a treatment-planning CT is taken. Consent is obtained after explanation (it can be withdrawn after signing). Treatment can be inpatient or outpatient, usually 4 times a week. After about 15 minutes of positioning, irradiation takes 3–4 minutes, with no pain or heat during irradiation.
Side effects
Most are mild, such as skin pigmentation or hardening under the skin. Decline in kidney function is usually very small. However, in patients with chronic renal failure severe enough that surgery would require immediate dialysis, function may worsen over time after treatment, and some have started dialysis.