Differences between chemotherapy, immunotherapy and biological treatment
Nowadays, it is very easy to get lost among the millions of web pages and social networks about cancer treatment (chemotherapy, biological or targeted therapy, immunotherapy (immunological treatment). Before starting treatment it is very important to know the basic concepts, and also to learn how to compare different types of treatment, depending on the type of disease.
The complexity of information on the cancer diagnosis prevents many patients from understanding its essence. Moreover, many of these pages are not accessible to the level of knowledge of a person or are based on current scientific facts, which can lead to confusion and hamper important decisions.
Cancer treatment groups contain dozens to hundreds of drugs that are constantly updated, which makes it even more difficult to make an informed decision about the course of treatment, even for those who have basic medical experience.
Below will be considered three main cancer treatment groups of medicines (chemotherapy, targeted therapy and immunotherapy) and the mechanism of their work.
Chemotherapy – the oldest group of drugs
In general, chemotherapeutic drugs focus on cellular mechanisms, which are expressed not only in cancer cells, but also in healthy ones. Some of these mechanisms are involved in the process of cell division, which naturally occurs in healthy cells, although it proceeds more slowly than in cancer cells. Thus, chemotherapeutic drugs traumatizes healthy cells, that explains many side effects of this method.
The percentage of reactions to chemotherapy varies depending on the type, stage of the cancer, the general health of the patient, and other factors. For example, about 70% of patients with certain types of bladder cancer can respond to chemotherapy, while patients with certain types of pancreatic cancer will respond to treatment in less than 10% of cases.
All approved chemotherapeutic drugs have proven to be safe and effective to increase the expected duration and quality of life of patients in large groups (clinical trials). However, this fact can not indicate the chances of the chemotherapy success in a particular patient, and to predict the certain side effects as well.
Despite such facts, chemotherapeutic drugs are the most common, oldest and most widely studied antitumor drugs. Science has been using them for about 70 years, and therefore they are the only group of drugs whose results and effects can be seen for many decades of treatment. And although these medicines were discovered so many years ago, there are constant news about this group of drugs also today. These achievements include developing new chemotherapeutic agents, adapting known chemotherapeutic agents to new tumors, reducing side effects of these drugs and their combination with other treatments, including immunotherapy and biological treatments.
Biological cancer treatment
Biological treatment methods are target drugs, selected for certain patients. While chemotherapeutic drugs work in both healthy and cancer cells, biological treatment is based on small particles, molecules that are expressed in cancer cells, and also focus on features that are unique in tumor cells. This is why these therapies are called target therapy and molecular methods of treatment.
For example, monoclonal antibodies uniquely bind to cancer cells and activate the immune system against them. Other biological drugs can bind to substances that release tumors and make them dis-activated. Biological methods of treatment not only promote the treatment of many types of cancer, but also forced the world of oncology to move on to a new generation of diagnosis: molecular diagnostics.
Molecular diagnostics allows to define a cancer type of a patient and better adapt the treatment to different patients, even if until recently their diseases were considered similar (precision treatment). This diagnosis allows you to more effectively regulate the drug protocol and avoid prior treatment with low success rates, especially when it is accompanied by significant financial costs and the risk of side effects.
However, targeted biological methods of treatment can not guarantee full therapeutic effectiveness and do not achieve significant results in all patients. It is important to know that although these drugs “work” in a relatively focused manner, they can also cause systemic side effects. It has been shown that even if approved biological treatments improve quality and survival in large groups of patients, it is not yet possible to predict in advance which patients will respond to treatment and how long remission will last.
Most of the treatments based on natural immunological components were approved only during the 2000s, and the number of them increased significantly every year.
Immunotherapy works in a number of incredibly complex mechanisms designed to use the body’s immune system to fight tumors. One of the most known families of this group of drugs is the inhibitor of the control point. These drugs, such as Pembrolizumab (Keytruda) and Nivolumab (Opdivo), help the immune system detect cancer cells and attack them.
In some cancers, mainly melanoma, NSCLC and head&neck cancers, immunotherapy led to a real revolution in treatment lines, with immunotherapy also being approved as the first or second line of treatment for certain diseases (after previous failure of chemotherapy).
Immunotherapy, as well as chemotherapy and biological therapy, can not guarantee an ideal result or the absence of side effects. Cancer cells, as a rule, develop mechanisms for “evading” the drug and, thus, reduce its useful time of action. This applies to all drugs – chemotherapy, immunotherapy and biological methods of treatment.
Currently, hundreds of clinical trials of immunotherapy drugs are being conducted, including in Israel.
It is important to know that drug therapy in any of the groups can be performed after a surgery to remove the tumor (known as adjuvant therapy) or before it (known as neoadjuvant therapy), depending on medical considerations and medical evidence of the success of these treatments in the past.
In addition, according to the type and stage of the disease, radiotherapy can also be included in the treatment. Treatment with surgical intervention will be preferable where possible, since surgery causes a prolonged remission of the disease in most cases of cancer.
Neoadjuvant therapy can reduce the size of the tumor and improve the chances of an effective resection during surgery, while adjuvant treatment (after surgery) can significantly reduce the likelihood of recurrence of the disease in the near future.
In addition, in some cases, palliative treatment may be considered. For example, when a tumor causes suffering to a patient. Such treatment is aimed at reducing the tumor and alleviating the pain, and not at a significant increase in life expectancy.