This is why it is so important to have a IPM Program (Integrated Pest Management). Eliminating the food source as well treating the are! This is something the Pest Technician and Home Owner will need to do hand in hand.
If left unchecked a cockroach infestation can rapidly expand it's numbers in a few weeks or months to become major risk to health and safety.
Modern science has the answer. A cockroach food bait that has a delayed lethal effect ... ensuring enough time for the bait to be transferred to other cockroaches by each others feces. The IGR bait is an insect growth regulator that stops the ability of the cockroach to replace its skin - made of "chitin". These IGR's are of ultra low toxicity to people. Applied as small blobs in cockroach habitat areas away from human contact, the gel-bait is highly attractive to cockroaches and provides effective control, usually for many months.
What you as the Homeowner can do.
Make your home unfit for cockroaches, where possible, take away their food, water and restrict shelter and access points into the kitchen and they will almost certainly move somewhere else.