What cell process is the target of most chemotherapeutic drugs and radiation?

Question

Why are these treatments useful for cancer?

Ok..I do not get this one at all.

Answer 1

Different chemo drugs target different parts of the cell cycle. Some inhibit DNA replication or transcription. Others inhibit the formation of the mitotic spindles that pull the two daughter cells apart. There are even some drugs that target specific receptors or proteins on the cell surface and send signals for the cell to die. Radiation causes damage to the cancer cells and inhibits the cell cycle as well.

Cancer cells are rapidly dividing cells and inhibiting the cell growth cycle causes the cancer cells to die and therefore makes the tumor get smaller and hopefully go away completely. Radiation and chemo drugs also kill normal cells, but most divide slower than cancer cells and are much more capable of recovering from the damage.

Answer 2

Chemo is supposed to target the cells that have mutated or are different to other normal healthy red and white blood cells, it is also like poisoning your body to kill the virus, but what the doctors don't tell you is that if you have large cell cancer (this is benign) they don't usually do anything unless it changes in size or colour but if you have small cell cancer this is malignant. Using chemo actually pushes the cancer and drugs used to kill it throughout your body, this is why there is often a secondary cancer occurrance within a few years, as it attaches itself to some other organ. When they use radiation, they have either caught it extremely early or you've had an operation to remove the cancer and they have got most of it.
The radiation therapy is to make sure that kill the rest (if any) is left. My family have been through both of these. My mum died after they found a mass on her lung that was cancerous, they decided because she was in her early sixties that it was best to opt for the chemo, wrong idea, it cleared her of lung cancer and we all celebrated until 6 months later they found it had moved to her brain, then her bone marrow, she fought hard but died at 65, way too young. My father in-law had throat cancer, had an op. but they found 2 more pin head sized
cancers on his voice box, they wanted to remove his voice box, he reckons if he can't talk he may as well be dead, so he had 6 weeks of radiation 5 days a week, he recently got the all clear, no scarring from the op. no sign of the cancer and only slight swelling has prevailed, which will subside in time. A neighbour has also had cancer in her bones for over 10 years its been dormant, she has never had chemo, but its on the march again and they are talking about it, I personally would so "go away" and live my life to the fullest if it wasn't found early, I reckon that chemo isn't the be all and end all, it makes you vomit, gives you ulcers in your stomach, makes your gums bleed and not apetite, but each to their own. That's my personal experience, I hope it helps you, goodluck!!!

Answer 3

Cells have genes which act as safeguards against functioning and dividing with damage to their DNA. These genes are known as tumor suppressor genes. Some well-known tumor suppressor genes include p53, PTEN, and Rb. These genes try to initiate cell suicide, a process known as apoptosis, thru a cascade of protein messages (signaling pathway).

Chemotherapy drugs may damage the DNA severely by crosslinking DNA, distributing micro-skeletal structure (tubulin) proteins or, some other method. When the cell attempts to divide, this damage is usually enough to cause apoptosis. Note, chemotherapy and radiation are most effective against rapidly dividing cells such as cancer cells and some healthy ones like intestinal lining, tongue, bone marrow and, hair cells.

However, cancer cells divide rapidly as a result mutate often. The mutant cancer cancers usually develop defense mechanisms against chemotherapy such as p-glycoproteins which act as pumps to eject the chemotherapy. Mutant cancer cells may develop the ability to repair DNA damage done by radiation.

One question you may have asked. If cancer cells commit suicide because of damage to DNA, how come the mutations that caused the cell to become cancerous not cause it to kill itself. The answer probably lies in the amount and location of the DNA damage. In other words, the cancer mutations may have prevented apoptosis and/or not been enough to cause it. While the DNA damage from chemotherapy and radiation is too much for even a cancer cell.

Answer 4

Mandalin gave you an excellent answer. I would like to add that a major process that many cancer therapies target is Programmed Cell Death (Apoptosis).