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What is Chemotherapy?


What is Chemotherapy?

Chemotherapy (chemotherapy) refers to chemical drug therapy, which refers to a treatment method that uses cytotoxic drugs to kill tumor cells. Chemotherapy, together with surgery and radiotherapy, was known as one of the three traditional cancer treatments in the past. Now with the rise of targeted therapy and immunotherapy, the status of chemotherapy is not as important as in the past, but it is still the cornerstone of tumor treatment.


Chemotherapy is a systemic treatment-based method, mainly through intravenous administration, but also by oral route, or by thoracic or abdominal perfusion. In some types of cancer, such as germ cell tumors, chemotherapy alone is often curative. In many other malignant tumors that cannot be cured by chemotherapy, the metastatic stage has already occurred. Chemotherapy is still one of the main treatment methods for cancer, which can greatly control the tumor progression and prolong the survival of patients. Of course, chemotherapy will inevitably have some toxic and side effects, so it must be administered to patients by doctors specialized in oncology.


Infographics showing process of chemotherapy

When was chemotherapy started and by who?

Chemotherapy inventor Paul Ehrlich Started in 1911.

Table of Contents

1. Origin

2. Ways

3. Principles of medication

4. Notes

5. Reasons for Failure

6. Main Impact

7. Whether or not to do chemotherapy?

8. Does Chemotherapy Work?



What is the Origin of Chemotherapy?

The term chemotherapy was first used by Paul Ehrlich, director of the Institute for Infectious Diseases and Serum Research.

In Liverpool, a synthetic arsenic compound has been tried to treat parasitic infections. But when Enlich tried to replicate the results, he found that the disease developed resistance to the drug. He asked chemists to try to synthesize many different arsenic compounds.

Later, in 1905, another German scientist, Fritz Schöding, discovered the microorganism that causes syphilis, a sexually transmitted disease. Enlich used his compounds to test therapeutics against the new microbe. He was pleased to find that compound 606 worked. He called the compound salflusan and dubbed it the "magic bullet" because of its special effects on syphilis. It was first used in the treatment of syphilis in 1911.

Since then, scientists have been looking for chemicals that can kill tumor cells without causing serious harm to the body. Scientists have to test thousands of chemicals before finding effective ones.

Many types of cancer can be cured. Interferons are proteins naturally produced by the body in response to certain viruses. They stimulate the body's own defense system and kill some cancer cells. They have been used successfully to treat certain types of leukemia and to slow the development of some tumors.


What are the ways to perform Chemotherapy?

There are four ways of clinical application of chemotherapy:

1. Systemic chemotherapy for advanced or disseminated tumors

Because other effective treatments are often lacking for patients with these tumors, chemotherapy is often used initially with the aim of achieving remission in the near term. This chemotherapy is usually called induction chemotherapy (Induction Chemotherapy). If the initial chemotherapy regimen fails, switching to other chemotherapy regimens is called Salvage Treatment.


2. Adjuvant Chemotherapy

It refers to chemotherapy after local treatment (surgery or radiotherapy) to prevent the recurrence and metastasis of micrometastatic lesions that may exist. For example, postoperative adjuvant chemotherapy in patients with osteosarcoma, testicular tumors and high-risk breast cancer can significantly improve the curative effect and improve the survival rate or disease-free survival rate.


3. Neoadjuvant Chemotherapy

For tumors that are relatively limited in clinical, but difficult to remove by surgery or radiotherapy, chemotherapy can be used before surgery or radiotherapy. 

Its purpose is to hope that the tumor will shrink after chemotherapy, thereby reducing the scope of resection and reducing the disability caused by surgery. 

Secondly, chemotherapy can inhibit or eliminate possible micrometastases and improve the survival rate of patients.

It has been proved that neoadjuvant chemotherapy can reduce the scope of surgery for bladder cancer, breast cancer, laryngeal cancer, osteosarcoma and soft tissue sarcoma, non-small cell lung cancer, esophageal cancer and head and neck cancer, or treat unresectable tumors after chemotherapy. become a resectable tumor.


4. Special route Chemotherapy

(1) This is applicable in Endovascular treatment, including cancerous intrathoracic, intraperitoneal and intrapericardial effusions. Usually chemotherapy drugs (such as mitomycin, cisplatin, 5-fluorouracil, bleomycin) are dissolved or diluted with an appropriate amount of fluid, and then injected into the body cavity of various lesions through a drainage catheter, so as to control malignant purpose of body cavity effusion.


(2) Intraspinal chemotherapy Leukemia and many solid tumors can invade the central nervous system, especially the meninges are the most vulnerable. 

The treatment method is usually intrathecal administration by lumbar puncture, so that there is a higher drug concentration in the cerebrospinal fluid, so as to achieve the purpose of treatment. 

Commonly used drugs in the spinal canal are methotrexate and cytarabine.

(3) Arterial intubation chemotherapy, such as external carotid artery branch intubation in the treatment of head and neck cancer, hepatic artery intubation in the treatment of primary liver cancer or liver metastases.

Selection and Application of Principles of Chemotherapy Medication

Although there are more than 40 kinds of commonly used anti-tumor drugs, and new drugs are still being developed, in order to achieve good curative effect, there must be a reasonable treatment plan. This includes the timing of medication, the selection and compatibility of drugs, and the order of administration, dose, course of treatment and interval time, etc.

Showing Selection and Application of Principles of Chemotherapy Medication

In order to achieve a comprehensive, reasonable and effective selection of combined chemotherapy regimens is necessary.

In general, the composition of the combination chemotherapy regimen should consider the following principles:

1. Use of drugs with different mechanisms of action in order to act synergistically

2. Drugs should not have similar toxicity, so as not to add to the toxicity and the patient cannot tolerate it

3. A single drug must be effective



(1) The diagnosis must be clear before starting treatment. Leukemia, multiple myeloma and malignant histiocytoma must be diagnosed by hematology and bone marrow cytology. Malignant lymphoma and various other solid tumors must be pathologically diagnosed by local tissue.

Chemotherapy drugs are generally not used for diagnostic treatment, let alone as a placebo, so as to avoid unnecessary losses to patients.

(2) The patient's general condition is good, and the blood picture and liver and kidney function are normal, so they can tolerate chemotherapy.

The type and dose of the drug should be carefully considered in any of the following situations:

  • Elderly and frail
  • Previously received multiple chemotherapy or concurrent radiotherapy
  • Abnormal liver and kidney function
  • Obvious anemia
  • WBC or platelet lower than normal value  
  • Malnutrition, significantly decreased plasma protein  
  • Tumor bone marrow metastasis
  • Adrenal insufficiency 
  • Fever, infection or other symptoms Complications
  • Cardiomyopathy, etc.
  • Chronic pulmonary insufficiency

What are the reasons of failure Chemotherapy?

Failure reasons of Chemotherapy:

1. Patient side

Insufficiency of bone marrow and other vital organs (liver, kidney, heart, lung, etc.), the general condition of the patient is too poor to tolerate chemotherapy.


2. Oncology

Primary or secondary drug resistance; the proliferation rate is low and there are more cells in the quiescent phase; the tumor burden is too large, and the tumor cells are more than 1011.


3. Drugs

The selectivity is not strong, and the damage to the tumor and normal tissue cells is not much different. It is ineffective or too ineffective for G0 phase cells; it cannot act on the tumor cells in the "refuge" such as cannot pass through the blood-brain barrier and enter the brain. Its most efficient usage has not yet been found.


Main influence

Even if you feel unwell during treatment, you can often recover quickly between sessions (during the pause in treatment), and you can resume your daily activities when you feel better.

If you are taking chemotherapy pills at home, chemotherapy will cause very little disruption to your daily life.

During the time of oral chemotherapy, you still depend on your own mental state, go to work and participate in various social activities as usual.

Some chemotherapy that requires intravenous injection can be done in a hospital outpatient department, but some cases do require a period of hospital stay, which requires more changes to your daily routine. But as long as you explain to your employer why you need a vacation, I believe most employers will understand.

For most patients undergoing chemotherapy, the occasional alcoholic beverage will not affect the effectiveness of the treatment.


Chemotherapy side effefcts

Whether or not to do chemotherapy?

In outpatient clinics or wards, doctors and patients often need to communicate treatment plans. When it comes to chemotherapy, many patients will be afraid or even refuse.


"Doctor, I don't want chemotherapy, chemotherapy will only go faster!"


"Doctor, can you not do chemotherapy, anyway, it's not cured, so don't suffer from this."


These reactions are either worried about the ineffectiveness of chemotherapy, or worry that the side effects of chemotherapy are too large to be worth the harm. It shows that patients have not yet established a correct understanding of chemotherapy, and there is a situation of partial generalization, which usually requires us to spend a lot of time and energy to explain patiently.

With everyone holding the view of "life first", let's talk about our objective understanding of tumor chemotherapy.

1. Is chemotherapy effective?

Chemotherapy (referred to as "chemotherapy") is one of the earliest "troikas" (surgery, radiotherapy, chemotherapy) for tumor treatment. In recent years, with the continuous emergence of new treatment methods, such as targeted therapy, immunotherapy, cell biological therapy, etc., the status of chemotherapy has been impacted to a certain extent. However, chemotherapy is still one of the main effective methods for the treatment of tumors.


Does Chemotherapy Work? 

First, on the definition of effect, doctors and patients may have different understandings. If the desired effect of the patient is a cure (term, complete remission), then most of the existing tumor treatment methods cannot achieve the biological characteristics of malignant tumors. Even if the early tumor is surgically removed, there are still some Transfer occurs. In fact, the vast majority of chronic diseases in the world cannot be cured. Therefore, the blind pursuit of healing is unrealistic. 

Controlling tumors as much as possible, delaying disease progression, paying attention to the time and quality of survival with tumors, and emphasizing "people-oriented, survival with tumors" are our reasonable expectations.


Then, under this consensus, the efficacy of chemotherapy is certain. A few chemotherapy-sensitive tumors, such as testicular cancer, leukemia, and Hodgkin lymphoma, can be completely relieved by chemotherapy alone, with a five-year survival rate of over 85%. 

For the vast majority of tumors, the purpose of chemotherapy is to stabilize or shrink the lesions, control tumor progression, and prolong life. 

The specific effect of chemotherapy for each individual will vary depending on the type of cancer, dose, whether it is combined with drugs, and physical conditions, and needs to be scientifically evaluated according to the actual situation. For example, the evaluation of the efficacy of solid tumors, the most commonly used RECIST criteria.


2. Are the side effects of chemotherapy great?

The earliest chemotherapy drug "nitrogen mustard" originated from the biochemical weapon "mustard gas" in war, and the modern arsenic trioxide is derived from the ancient "king of poisons" arsenic. It seems that chemotherapy is equivalent to taking poison, which is "chronic suicide". However, the purpose and mode of administration of the two are vastly different. 

Although chemotherapy drugs kill tumor cells by mistake, they also accidentally injure normal tissue cells, but tumor cells are more vulnerable to attack. It is this "limited selectivity" feature of chemotherapy drugs that makes people love it and hate it. 

Usually, chemotherapy is more likely to damage normal cells that are growing and dividing vigorously, such as gastrointestinal epithelial cells, bone marrow hematopoietic cells, hair follicles, etc., resulting in symptoms such as nausea, vomiting, diarrhea, hair loss, and cytopenias. However, these symptoms do not occur in everyone, and most of them are reversible. With the metabolism of the drug, the symptoms will gradually ease, and serious adverse reactions are only rare cases. 

Importantly, there are also many drugs (including Chinese herbal medicine) and methods that can relieve the corresponding symptoms in clinical practice. Therefore, it is not necessary to give up chemotherapy just for fear of adverse reactions.


3. Under what circumstances is chemotherapy suitable for use?

Chemotherapy is administered orally or intravenously, and the drug is delivered to various organs of the body through the blood circulation, thereby killing tumor cells. Unlike local treatments such as surgery and radiotherapy, chemotherapy is a systemic method of administration. In theory, chemotherapy is suitable as long as there are sensitive tumor cells in the body. So, under what circumstances is chemotherapy appropriate?


1) Chemo-sensitive tumors, such as leukemia, multiple myeloma, malignant lymphoma and other hematological tumors, chorioepithelial carcinoma, testicular cancer, small cell lung cancer, etc., can be well controlled by chemotherapy.


2) Adjuvant chemotherapy after surgical resection of solid tumors and/or local radiotherapy, using chemotherapy to eliminate residual tumor cells can reduce the probability of tumor metastasis, thereby prolonging the life of patients.


3) The solid tumor has extensive or distant metastasis and is not suitable for surgery or radiotherapy; if the solid tumor recurs after surgery or after radiotherapy, chemotherapy can be used to stabilize or reduce tumor lesions, control disease progression, and prolong survival.


4) Neoadjuvant chemotherapy before surgery, using preoperative chemotherapy to shrink the lesions and increase the probability of radical surgical resection.

Similarly, chemotherapy has corresponding contraindications, that is, those who are not expected to tolerate or benefit from chemotherapy: 

i.) Elderly and frail, poor nutritional status, unable to tolerate chemotherapy, and the expected survival time is less than 2 months.


ii.) Insufficiency of important organs, such as liver, kidney, heart and lung, bone marrow hematopoietic function, etc. have more serious dysfunction.


iii.) Those who have serious infectious diseases such as chickenpox and herpes zoster, and those who are allergic to chemotherapy drugs.


iv.) For women who are pregnant and breastfeeding, most chemotherapy drugs are contraindicated, and a few are used with caution.


v.) Psychiatric patients who cannot cooperate with treatment


4. How many times of chemotherapy do cancer patients need?

Since chemotherapy can destroy tumor cells, why can't chemotherapy be performed in one treatment, but in multiple cycles? 

This is due to the "limited selectivity" characteristic of chemotherapy. The human body cannot withstand too many chemotherapy drugs at one time, and one chemotherapy can only destroy a certain percentage of tumor cells. By dividing the chemotherapy dose into multiple treatments in a multi-cycle manner, more tumor cells can be eliminated without causing serious adverse reactions.


The frequency of chemotherapy is determined according to the specific condition of the patient (tumor location, pathological type, clinical stage, etc.). For example, 4 times of adjuvant chemotherapy is usually performed after surgery for early-stage tumors. 

If postoperative pathology shows high risk factors such as vascular tumor thrombus or nerve invasion or lymph node metastasis, 6 or more times of chemotherapy are required.

For palliative chemotherapy, after 2 cycles of chemotherapy, the efficacy will be evaluated by CT, MRI and other means. If it is effective, chemotherapy will generally be continued; on the contrary, if it is ineffective, the chemotherapy regimen will be changed according to the guidelines, and post-treatment evaluation will be continued. 

Understanding Chemotherapy under Conditions

Colds are one of the most common diseases we suffer from. Some people have other diseases secondary to a cold, such as viral myocarditis, bacterial tracheobronchitis, pneumonia and meningitis, and so on. This type of disease is due to the changes in bodily functions after the body is invaded by pathogenic organisms, and belongs to infectious diseases. Infectious diseases and tumors are the first diseases caused by pathogens invading the body


The second type of disease, similar to the elderly often suffer from certain chronic diseases, such as coronary heart disease, diabetes and so on. People who love sports and outdoor activities often experience dehydration and heat stroke. This large category of diseases is caused by abnormal functions of the patient's body tissues and organs due to a variety of reasons. Such as organ function enhancement, the function is higher than the normal level, called hyperfunction. Organ function is weakened, and the function is lower than normal, which is called hypofunction. Representative diseases such as hypertension, hypotension, hyperthyroidism, hypothyroidism and so on. 

The treatment of such diseases is carried out by exciting or inhibiting the function of the corresponding system, organ or tissue of the body. Therefore, the drug is directly aimed at the patient's body.


For the treatment of the first type of disease, because its cause is the infection of bacteria, viruses and other pathogenic organisms or the body produces tumor cells, the target of the treatment is not the patient's body, but the pathogen. 

Chemotherapy is a general term for drug treatment of all pathogens that cause diseases. Pathogens include viruses, bacteria, fungi, parasites and tumor cells.


From this, we know that "chemotherapy" is a large class of drug treatment, which is the use of drugs to treat viral infections, bacterial infections, fungal infections, and parasitic infections, including the treatment of malignant tumors. 

The scope of this concept is very broad, including but by no means limited to the treatment of anti-malignant tumors. So, let's not get scared when we hear about chemotherapy. Because we usually see chemical treatment everywhere, for example, if you suffer from athlete's foot, applying ointment for athlete's foot is performing chemical treatment. If you suffer from trachoma, chloramphenicol eye drops or erythromycin eye ointment for trachoma are also treated with chemotherapy.


Chemotherapeutic drugs (chemotherapy drugs)

All chemical substances that have selective inhibitory or killing effects on invasive pathogens, but have no or only mild toxic effects on the body (host).


There are many types of pathogens, including viruses, bacteria, mycoplasma, chlamydia, rickettsia, spirochetes, fungi, parasites and tumor cells. 

Correspondingly, there are many types of chemotherapy drugs, including antiviral drugs, antifungal drugs, antibacterial drugs, antiparasitic drugs and anticancer drugs.


Infections with different pathogens should be treated with corresponding types of chemotherapy drugs. And in addition to empirical selection of drugs, it is best to choose according to the type of sensitive drugs after pathogen detection and drug susceptibility testing.

Staphylococcus aureus is one of the most common pathogenic bacteria. It is ubiquitous in nature and can be found in the air, water, dust, and human and animal excrement.  

This is E. coli, and the therapeutic E. coli infection is a zoonotic disease that often causes severe diarrhea and sepsis.

In addition to this, there are various parasites, which are roundworms in the intestines

This is a parasite carried by aquatic products


Top cause of death before Chemotherapy

Whether it is bacterial infection, viral infection, or parasitic infection, pathogenic organisms invade the body and cause disease. Before the invention of effective chemotherapeutic drugs, such diseases were the number one cause of death in humans. In addition, our body can also produce tumor cells. 

When tumor cells escape the monitoring of the body's immune system and multiply, it will endanger people's lives. Malignant tumors are the diseases that cause the highest mortality rate in humans today. Therefore, for infectious diseases, malignant tumors must be actively treated. Among them, chemotherapy, that is, treatment with drugs, is a very important means.


Chemotherapy drugs are classified according to their effects: antibacterial, antiviral, antifungal, antiparasitic and anticancer drugs. Among them, there are many kinds of antibacterial drugs and the most used ones.

The scope of antibacterial treatment is not limited to bacterial infections. Some antibiotics are also used to treat chlamydia, mycoplasma, rickettsial infections and more.

There is also a special class of antibacterial drugs, called anti-tuberculosis drugs, which are specially used to treat tuberculosis.


Chemotherapy drugs are complicated, and their use must be carried out under the guidance of a professional doctor. 

Never take it for granted and use it indiscriminately by feeling, because the medicine is not symptomatic and may make the treatment ineffective and delay the disease. 

If it is not used properly, it may develop drug-resistant bacteria for itself, and eventually become incurable.



In conclusion, the formulation of the number of chemotherapy is not a personal empirical decision of the doctor, but is based on the analysis and summary of clinical trial data. In this regard, you can refer to the CDC or FDA guidelines. Chemotherapy is the abbreviation of chemical drug therapy, which is a treatment method that uses chemical drugs to prevent the proliferation, infiltration, and metastasis of cancer cells, and finally kill cancer cells. It is a systemic treatment, and together with surgery and radiotherapy it is called the three major treatments for cancer.  


Author's Bio

Name: Ian Skyler

Education: MBBS, MD

Occupation: Medical Doctor 

SpecializationCommunity Medicine, General Surgery, Natural Treatment

Experience: 18 Years as a Medical Practitioner


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