system
Given the following post, respond as if you're commenting on Reddit:
human
[LotR] How old can Orcs get?

Assuming they weren't murdered, or fell ill from poison or disease?
gpt
> They could be slain, and they were subject to disease; but apart from these ills they died and were not immortal, even according to the manner of the Quendi; indeed they appear to have been by nature short-lived compared with the span of Men of higher race, such as the Edain.

~Morgoth's Ring "Myths Transformed"

So they weren't immortal, and were apparently short-lived compared to Men of "higher race". What does higher race mean in this context? Tolkien mentions the Edain, but the Edain of the First Age had an average lifespan of 70-100. The problem with Orcs living shorter lives than the original Edain is that we have one documented lifespan of an Orc: Bolg. Bolg's father, Azog, was slain in 2799 TA, and Bolg himself was killed at the Battle of the Five Armies in 2941 TA. So Bolg must've been at least 142 at the time of his death, which means that either he was just an exceptionally long-lived Orc or that Orcs live longer than the Edain of the First Age. So in that case, Tolkien might've been referring to the Numenoreans, direct successors of the Edain. They lived 200-400 years, depending on their bloodline, so if Orcs are living to around 150, then they would be "short-lived" compared to the Men of "higher race". 

So in other words, Orcs could live to the age of 140+, but they probably didn't live much longer than that. And it's likely that few Orcs actually made it to Bolg's age, considering the violent nature of Orcish society.