Overrun

If the host body dies while the chestburster inside is still undeveloped & in the infant stages of its life cycle, both will likely die, at least according to the Alien films, although this has technically never been proved.

As far as the sacrificial chamber in AVP, there were actually quite a few hosts in there, around 6-7 if I recall, not to mention the several people that were later captured & used as hosts by the aliens as well.

My thinking is (hinting from the alien movies) Since the people with the chest bursters inside them wanted them to kill them mabey that hints that if they killed them it would stop the Chest burster from bursting. Mabey there is a second way for chest burters to develope, like a emergency way like there is something isnide the egg that the Face hugger can emplant the tube in and the chest burster growns inside the egg and eats the egg to grow or something.

Think of the alien growing in your body as a women with a baby growing in her, if she dies the baby dies. Stalker did a good job in explaining it. Kudos to him