Response Chemotherapy

Response to Chemotheraphy

Response to Chemotheraphy

   
With the exception of adjuvant chemotherapy, in which the presence of cancer is not noticed, the effectiveness of chemotherapy on cancer cells is measured in terms of the "response." Techniques to monitor responses may be similar to the tests used to diagnose cancer.

A lump or tumor that affects some lymph nodes can be palpated and measured externally through a physical exam.
Some internal cancerous tumors can be seen on an X-ray or CT scan and can be measured with a ruler.
Blood tests can be performed, including those that measure organic function.
In the case of certain types of cancer, a tumor marker test can be done.
Regardless of the test used (whether blood test, cell count or tumor marker test), it is repeated at specific intervals, so that it is possible to compare the results with previous tests of the same type.

How do you define the answer?
The response to cancer treatment is defined in several ways:

Complete answer: Complete disappearance of cancer or tumor; There is no evidence of the disease. A tumor marker (if applicable) may descend within the normal range.
Partial response: The size of the cancer has decreased by a percentage but the disease is still present. A tumor marker (if applicable) may have dropped but continues to show the disease.
Stable disease: The cancer has not increased or decreased in size; The state of the disease has not changed. A tumor marker (if applicable) has not varied significantly.
Disease progression: The cancer has grown; The disease is now greater than before treatment. The tumor marker test (if applicable) indicates that a tumor marker has increased.
When is the response measured?
In a newly diagnosed person who has been prescribed chemotherapy for cancer, the number of treatments is fixed. For example, an oncologist will prescribe a specific number of chemotherapy cycles according to the treatment protocol. Responses can be measured during chemotherapy, but the number of cycles usually does not change unless the cancer grows. If the cancer grows, chemotherapy is likely to be interrupted or a drug changed.

In a person suffering from a recurrence or advanced disease, a specific number of cycles may not be prescribed. Instead, 2 or 3 cycles are administered and then the response is evaluated. If the disease is stable or reduced, additional chemotherapy may be given as long as the responses are maintained, and provided that the toxicity of chemotherapy is tolerable. In general, a minimum of 2 or 3 cycles of chemotherapy is required to measure the response. A chemotherapy cycle may not be adequate to assess its effectiveness.

Combination chemotherapy

Combination chemotherapy is usually more effective than single-agent therapy.

When combining chemotherapy agents, factors to consider include:

• Antitumor activity 
• Different mechanisms of action 
• Minimally over lapping toxicities

The reasons for administering combination chemotherapy include:

  

• Overcoming of preventing resistance 
• Cytotoxicity to resting and dividing cells 
• Biochemical enhancement of effect 
• Rescue of normal cells

Factors affecting response to chemotherapy:

• Tumor cell heterogeneity 
•  Drug resistance 
•  Dose intensity 
•  Patient specific factors 
•  Poor functional status 
•  Impaired Organ function 
•  Concomitant disease