The needed change in the "war on cancer" will not be on the types of drugs being developed, but on the understanding of the drugs we have. The system is overloaded with drugs and underloaded with the wisdom and expertise for using them.
Cancer patients usually undergo four or five courses of chemotherapy before medical oncologists can tell whether the treatment is having an effect. By that time, the tumor may have grown so large that it is too late to switch to another chemotherapy regimen or the patient may be so weakened by the treatment that trying another approach is not immediately feasible. Medical oncologists treat a lot of patients but they don't know going into treatment if it's going to work.
A major obstacle in controlling cancer growth and metastasis in patients is the widespread inappropriate use of anti-cancer drugs. As the increasing numbers and types of anti-cancer drugs are developed, oncologists become more and more likely to misuse them in their practice. Between 2002 and 2004, 395 cancer drugs were submitted for clinical trials.
It would be highly desirable to know what drugs are effective against particualr cancer cells before these cytotoxic agents are systemically administered into the body. Cell culture assays are clinically validated drug tests on living specimens of cancer cells to determine the optimal combination of chemotherapy drugs. These assays are specifically tailored for each individual patient based on tumor tissue profiling, with no economic ties to outside healthcare organizations, and recommendations are made without financial or scientific prejudice.
Recommendations are designed scientifically for each individual patient. Various assays are performed on a tumor sample to measure drug activity (sensitivity and resistance). This will determine not only what drug or combinations of drugs will not effectively work, but which will be most effective for an "individual's cancer. Then a treatment recommendation is developed through what is know as "assay-directed" therapy.
At one time, chemosensitivity testing was considered unreliable because it was only fifty percent accurate and it took too long to get the results. Today, preliminary results are completed in about seven days and chemosensitivity testing has progressed to the point where it is <90% effective.
The key to improving drug sensitivity tests is related to the number and types of drugs tested. The more anti-cancer drug types there are in the selective arsenal, the more likely the system is to prove beneficial. In order to acquire sufficient data, tumors are tested with at least two assay endpoints, and most often three, for sensitivity in any one patient. On average, up to twenty drugs and combinations at two concentrations in three different assay systems, is an effective way to avoid false-positive or false-negative data. Careful choice of drug doses and administration intervals also improves outcomes.
Conventionally, chemotherapy is prescribed by medical oncologists according to fixed schedules. These schedules are standardized drug regimens that correspond to specific cancer by type or diagnosis. These schedules, developed over many years of clinical trials, assign patients to the drugs for which they have the greatest statistical probability of response.
However, patients with cancers that exhibit drug resistance are on the wrong side of the probability curve. They will likely receive treatments that are wrong for them. A failed attempt at chemotherapy is detrimental to the physical and emotional well-being of patients, financially burdensome, and may preclude further effective therapies.
Every cancer patient should have his/her own unique chemotherapy trial based on consultation of pathogenic profiles and drug sensitivity testing data. Research and application of drug sensitivity assays are being encouraged by growing patient demands, scientific advances and medical ethics. Drug sensitivity tests are not a luxury but an absolute necessity, and a powerful strategy that cannot be overlooked.
A chemo-induced gene mutation can happen when the original chemo received does not work. The cancer comes back. When it does this, the cancer comes back more aggressively. The mutagenic effects (changes in form) of chemotherapy on a genetically-unstable tumor, drives the tumor into a state of more aggressive behavior.
A cell culture assay uses living tumor cells to determine which drug or drug combination induces apoptosis (cell death) in the laboratory. Each patient is highly individualized with regard to sensitivity to chemotherapy drugs. A patient's responsiveness to chemotherapy has its own unique individuality.
There has been a veritable deluge of new approvals of cytotoxic drugs in recent years as the tortuous FDA process has been speeded and liberalized. In many cases, a new drug has been approved on the basis of a single very very narrow indication. But these drugs may have many useful applications, and it may take years to find out. Cell culture assay testing offers a way of seeing if any of these new drugs might apply to an individual's specific cancer.
Source: Various Bio-Assay Labs