It is well known that the present dominant approaches to cancer therapy - meaning toxic, damaging chemotherapy and radiotherapy, only slowly giving way to immunotherapy - produce a significant burden of senescent cells. Indeed, forcing active cancer cells into senescence is the explicit goal for many treatments, and remains an aspirational goal for a large fraction of ongoing cancer research. Most senescent cells self-destruct, or are destroyed by the immune system, but some always linger - and more so in older people, due to the progressive incapacity of the immune system. An immune system that becomes ineffective in suppressing cancer will be similarly ineffective when it comes to policing tissues for senescent cells.

An increased burden of lingering senescent cells is a good deal better than progressing to the final stages of metastatic cancer, that much is true, but those who undergo chemotherapy understand that it is the second worse option on the table. It has a significant cost, even when completely successful. Cancer survivors may lose as much as a decade of life expectancy, and have a higher risk of suffering most of the other chronic diseases of aging. These consequences are most likely due to the presence of additional senescent cells generated by the treatment, over and above those produced over the course of aging.

The open access paper here provides supporting evidence for (a) the presence of senescent cells following radiotherapy to be harmful to patients, and (b) the removal of those errant cells to be beneficial, reversing the harms done. Senescent cells are in many ways the ideal type of damage to occur during aging: their inflammatory secretions actively maintain a harmful state of cellular metabolism in the surrounding tissue, and that stops the moment they are destroyed. Destruction is far easier to achieve than repair of structures or delivery of replacement parts, and this is perhaps one of the reasons why senolytic therapies to remove senescent cells are the first form of rejuvenation therapy from the SENS portfolio to be developed in earnest.

Restored immune cell functions upon clearance of senescence in the irradiated splenic environment