The great consolidate.
Top Line: A common conundrum in the era of ablative radiation for oligomets is whether or not to treat the primary tumor site in addition to distant sites.
The Study: It turns out the question of whether to provide local therapy to the primary tumor in the setting of metastatic disease is a question about as old as the concept of oligometastatic disease. Here is a meta-analysis of 11 prospective trials dating back to 2004 that randomized nearly 5K patients receiving systemic therapy for metastatic disease to +/- the addition of local therapy to the primary tumor be it surgery or radiation. Overall there was no detectable improvement in overall or progression-free survival with the addition of local therapy. But wait. There was definitely no improvement in progression-free survival among those who received the addition of surgery (n=913, HR 1.15) but there was a detectable difference among those who received the addition of radiation (n=1558, HR 0.73). The biggest advantage was seen when radiation to the primary site was added for “low burden“ metastatic disease where the risk of death was notably reduced (HR 0.66). Note, low burden was defined differently per trial but was never more than 5 sites outside the axial skeleton. Most importantly, these were of course completely different trials with different inclusion criteria. The survival benefit with radiation was driven largely by prostate cancer that has a unique biology and trajectory, as well as nasopharyngeal cancer that has clear reasons why local tumor control could extend survival. Surgery, on the other hand, was dragged down considerably by failures with breast cancer.
TBL: While there is no broad benefit from local therapy to the primary site in unselected patients with metastatic disease, local therapy may be beneficial for select primary tumors and metastatic disease states. | Ryckman, Int J Radiat Oncol Biol Phys 2022