Stage 4 Prostate Cancer: Can Understanding Oligometastasis Help?

Upon hearing that your cancer has metastasized, introducing the nerve-wracking label “Stage 4” may trigger uncomfortable thoughts of fear and worry. Could it have already spread too far? Is it too late?

Advanced cancer is a complex disease, with many different presentations and a complicated outlook. Currently however, it is treated in a binary manner — either it has metastasized, or it has not. When it comes to deciding the best treatment for metastasized cancer, there is difficulty in differentiating between early and advanced, widespread metastasis. Experts have since begun to propose that a new perspective should be taken towards treating those with early metastasis (up to a few lesions beyond the original tumor).

The idea originated from Hellman and Weichselbaum in 1995, researchers from the University of Chicago. They believed that treatments typically only used for the original tumor could still help patients facing early metastasis through metastasis-directed therapy (MDT). To classify and differentiate this state better when planning cancer treatments, they proposed that a new, intermediate stage of metastasis should be identified — oligometastasis.

While this new state is still being characterized, there have been successes in identifying its molecular signature and strategies of invasion and metastasis in the body. Oligometastatic prostate cancer typically has fewer than five lesions, usually found in the bones in the body’s core (e.g. ribcage, skull, spine), rather than the limbs.

Recent trials have shown positive outcomes when using a combination of hormone therapy with either androgen receptor-targeted agents or chemotherapy for oligometastatic prostate cancer. Furthermore, while radiation therapy is typically only recommended for early disease or palliative relief after the cancer has spread, new work has also shown the value of stereotactic ablative body radiotherapy on improving patient outcomes during the oligometastatic state. However, long term-outcomes for this treatment have not been defined as yet.

As a new theory still in its nascent stages of growth, researchers will need much more data on oligometastatic disease to more accurately identify and support treatment of this cancer state safely and effectively. However, once validated, it may shift the care paradigm for some suffering with metastatic prostate cancer and introduce new hope for a treatable disease, rather than resignation to a palliative approach.