What are oligometastases?
In the past, once metastasis was found, microscopic metastases invisible on imaging were assumed, so local treatment was not given. However, with the concept of “oligometastasis”—a state with only a few metastases before the cancer spreads throughout the body—the value of local treatment for metastatic lesions began to be recognized. A typical example is resecting lung or liver metastases together with the primary tumor in colorectal cancer.
Advanced Medical Care in Japan
Carbon ion therapy for metastatic tumors is provided as Advanced Medical Care for ① up to 3 metastatic lung tumors, ② up to 3 metastatic liver tumors, and ③ a small number of lymph node metastases.
Conditions for lung metastases
Regardless of the primary cancer type, there must be no more than 3 metastatic lesions and no other evident lesions, including the primary (the primary must have been treated). Because the volume of lung in the irradiated area can be reduced, patients with low lung function may also be considered.
Conditions for liver metastases
As with lung metastases, regardless of the primary cancer type, there must be no more than 3 metastatic lesions and no other evident lesions, including the primary (the primary must have been treated). Cases treated on short schedules of about 1 to 4 fractions have been reported.
Conditions for lymph node metastases
There must be no recurrence of the primary tumor and no active cancer lesions other than the target lymph nodes. Even when several nodes are fused and hard to count, they are eligible if confined to a small region. Lymph nodes are often surrounded by organs at high risk of side effects, such as the digestive tract, which can make a sufficient X-ray dose difficult; with carbon ion beams, which can concentrate the dose, treatment is often possible.