This question suggests that we have, on average, 50-70 billion cell divisions per day. I just read that cancer cells divide more often and are therefore more prone to radiation.
I am wondering, for a specific type of cancer, how fast cancer do cells divide (approximately) compared to normal cells. Does the ratio of cancer mitosis rate to the normal cell mitosis rate varies a lot?
I checked bio-numbers but there's not much data there.
Tumors can be benign (they don't bother you at all eg: a mole which does not change) and malignant (also called cancer).
The difference is based on:-
Coming specifically to rate of growth, these factors must be considered:
This is taken from Robbin's Text book of Pathology,Ed.8, chapter 6
Edit 1: To know the numbers you need, you have to find out the rate of increase in volume (by measuring size at two points in time) and divide it by the approximate volume of one cell. This will give you the number of cells that has newly divided within the two measured points (growth in interval). Which can then be converted to cell divisions per second.
As pointed out, the rate is going to vary extremely, based on the cancer type.
Different cancers divide at different rates. One way to qualitatively visualize this is observe hair loss in patients who are undergoing chemotherapy. Commonly, a drug like cisplatin will be administered which will cross-link DNA, inhibiting cell division by activating apoptosis. Tissues which are killed most readily by cisplatin are those which are dividing most rapidly: intestines, head hair, red and white blood cells, tumors.
Despite the loss of hair on the head, many patients do not lose slower growing hair on their arms, eyebrows, eyelashes, etc. Likewise, though cell death in the intestinal lining may be dramatic on cisplatin, the skin may not show lesions as it is a more slowly dividing population of cells.
The rate of cell division correlates with the rate of cell death while taking the chemotheraputic drug cisplatin.
You may make a rough visual survey of the cells in the body which divide so rapidly that they die, and divide so slowly that they largely survive chemotherapy.
The rate of cell division of head hair and other body hair spans the rate of cell division over which cisplatin effectively acts on tumor cells.
I think you should start with immortalized cell lines and so in vitro division rates by perfect conditions. This is easier to measure than in vivo division rates. E.g. HeLa has a division time of 23 hours. MDA-MB-231 and A549 division times are around 28 hours.
So I assume there is a physical barrier somewhere around one division per day or so, and it simply cannot grow faster. While bacterial division times are much lower (down to 20min), they also depend on special mechanisms (see this question/answer) and are orders of magnitude smaller than mammalian cells, so they don't count as a counter argument to this.
If you check zygote division times (10-12h, 14-16h, 22-24h, ...), you can see that they highly depend on the cell size. After some divisions the zygote depleted the reserves necessary to divide at higher rates, so after that it is limited by the ~24h barrier too.
Same 24h data here by rapidly proliferating cells.
So we can assume that 1/24h is the maximum rate of cell division by cancer. Let's read more about cancer in vivo, because it behaves completely different than immortalized cell lines in in vitro tests.
Originally tumours were thought to grow because they consisted of cells that multiplied more rapidly than cells in the surrounding tissue. In fact the average cell cycle of 48 hours for human tumour cells is slightly longer than the cycle of non-malignant cells. ...
When a normal cell divides, it does os only to replace a cell that has been lost and in this way a constant cell population is maintained. In tumour cells the control mechanism appears to have been lost: as the cell divides it adds to existing numbers of cells and increases the total population. ...
A measure of the rate of tumour growth is the time taken for a given population of malignant cells to double in size (doubling time). If the cell cycle takes between 15 and 120 hours, the doubling time can be between 96 hours and 500 days, depending on the histological type of the tumour, its age and whether it is a primary or metastatic growth. A shorter doubling time (less than 30 days) can be between is seen with teratomas, non-Hodgkin's lymphomas, and acute leukaemias; common solid tumours such as squamous cell carcinoma of the bronchus and adenocarcinoma of the breast and bowel have doubling times in excess of 70 days. In the patient the growth of a cacncer is only detectable and observable during the last 10-14 of its 35-40 doubling times.
So according to this book the division rate of cancer cells are similar to healthy cells.
According to another book this statement is from Dougherty & Bailey 2001, but I wasn't able to find the scientific article. :S
Tumour cells appear to have lost control mechanisms which prevent cells from growing until replacement is required. Human tumour cells are thought to have an average cycle time of 48 hours. This is not more rapid than the cycle of most normal cells. The reason tumours become larger is because their cell division creates additional cells rather than replacements (Dougherty & Bailey 2001).
Please notice that cancer cells do not grow or divide faster than normal cells, although many people believe that, and most forms of chemotherapy were designed on the assumption that they grow faster. Actually, what makes cells cancerous is the lack of control of cell growth, so that they keep on growing without limit, even if slowly. On the other hand, some kinds of cancer cells do grow quite rapidly, even if not faster than certain normal cell types, such as those in the bone marrow that constantly replace blood cells, and those in the intestinal lining and skin (including hair follicles) that constantly renew those structures. In one form of lymphoma, the abnormality has nothing to do with growth or division at all, but instead is a lack of apoptosis (programmed cell death), so that the cells accumulate without limit.
Cancer in One Easy Lesson by Biology 166 Unsolved Problems in Cell Biology Albert Harris
