Cancer surgery is a procedure to repair or remove part of the human body to achieve different goals, from the diagnosing and treatment of cancer to relieving the symptoms that the disease causes. Surgery remains the foundation of cancer treatment. It may be the only treatment, but could also be supplemented with other treatments, such as radiation, chemotherapy, hormone therapy, biological therapy, and targeted therapy. Removing the cancerous tissue as completely as possible is the aim of any treatment designed to bring about a cure. The removed tumor tissue is carefully analyzed to determine whether it is cancerous (malignant) or noncancerous (benign) and to define how advanced the cancer is (staging). This information helps to decide on further steps in anticancer therapy. Many patients with tumors in the breast, lungs, stomach, bowel, ovaries, or uterus or on the skin can be cured by surgery when performed at an early tumor stage. A cancer patient is considered cured if no relapse occurs within the five-year period following treatment.
Less invasive surgery
New techniques such as laser surgery and endoscopy enable minimal invasive treatments in comparison to treatments years ago. One example of this is the surgery of tumors in the breast: It is often no longer necessary to remove the entire breast. However, breast-conserving surgery is generally accompanied by radiation therapy in order to kill off the remaining tumor cells within the breast tissue. The basic rule for all surgical procedures today is: as thorough as necessary, but as noninvasive as possible.
Advances in genomics and cell biology have increased the opportunity for the rational design of targeted drugs to inhibit the function of specific molecules, including those contributing to the proliferation of cancer cells. But there are multiple redundancies, or alternate routes in cellular pathways, that may be activated in response to the inhibition of a single pathway. This redundancy promotes the emergence of resistant cells under the selective pressure of a targeted drug, which can result in drug resistance. Therefore, although targeted therapies may offer enhanced efficacy and improved selectivity, their effects might not be durable when used alone (monotherapy).
Alternatives to monotherapy
For the reasons described above, combination therapies might be needed to effectively treat tumors. Combination therapy is the use of more than one medication or other therapy simultaneously.
Simultaneous drug administration can be achieved by giving separate drugs, or, where available, by giving combination drugs which contain more than one active ingredient. Combination therapies could potentially reduce the possibility of developing drug resistance, since a tumor is less likely to develop resistance to multiple active ingredients or therapies simultaneously.
In the future, tumors may be screened for pertinent pathway dependencies, as is currently already done for breast cancer, and patients will be treated with drug combinations on the basis of screening results and experience with patterns of resistance.
Radiation therapy is the medical use of ionizing radiation to control or kill malignant cells and is another cornerstone of cancer treatment. More than half of all cancer patients are treated with this kind of therapy over the course of their illness. Radiation therapy plays a part in over a third of all successful recoveries and is a completely local measure. In other words, a tumor can only be eliminated within the irradiated area.
A series of malignant diseases, including laryngeal and prostate cancer, can be treated by exposure to radiation therapy alone, without the organ having to be removed. Even if a complete cure is not possible, radiation treatment may prevent, or alleviate, discomfort.
The way radiation therapy works
Radiation therapy is mainly conducted using electromagnetic and particle beams, which damage the DNA, serve to disrupt cell division, and slow down the growth of cancer cells, which are constantly proliferating cells. Radiation is able to modify the genetic makeup - i.e. the genes of cells - in a way that eliminates their ability to divide and causes them to go into programmed cell death (apoptosis).
In Germany, around 15,000 patients a year are cured with conventional chemotherapy, which is also known as cytostatic treatment.
Particularly impressive results have been achieved in combating certain childhood tumors. Cancer patients were first successfully treated using medication in the 1950s (with methotrexate, which is still in use today).
Nowadays, there are around 50 different cytostatic drugs.
Side effects of chemotherapy
The most common chemotherapy agents work by killing cells that divide rapidly in the human body - one of the main characteristics of most cancer cells. This means that chemotherapy also harms cells that divide rapidly under normal conditions, such as cells in the bone marrow, the digestive tract, and hair follicles. This leads to significant side effects like hair loss, nausea, and diarrhea. Other serious side effects can even lead to treatment being stopped, for instance if severe inflammation of the mucous membranes or a drastic reduction in the number of white blood cells occurs.
Further possible limitations of chemotherapy
Another limitation of treatment with cytostatic agents is that they have little or no effect on certain types of cancer. In addition, cancer cells can develop resistance to certain treatments which - like the down regulation of the body´s immune response to the malignant cells - is one of several survival strategies used by tumors.
Targeted therapies are becoming increasingly important to treat cancer patients more specifically. This involves drugs that block the growth of cancer cells by interfering at a cellular level with specifically targeted molecules (targets) needed for carcinogenesis and tumor growth, rather than by simply interfering with rapidly dividing cells, as is the case in traditional chemotherapy. Targeted cancer therapies may be more effective than current treatments and less harmful to normal cells.
Kinases as target in cancer therapy
One example of an important player in this field are kinases (= enzymes). These protein molecules function like switches, frequently controlling complex signaling pathways and a cell´s growth. If a kinase is activated, the cell can divide and proliferate. Deactivating these proteins can thus interrupt a signaling cascade, meaning the nucleus doesn´t receive a signal to divide. In cancer cells, such kinases are often mutated and activated, forcing the cells to divide continuously - they become immortal. Treating cancer cells with small molecules which block the respective kinase activity can lead to the death of these cells.
Antibodies in cancer therapy
Another important group in the area of targeted therapies are monoclonal antibodies, which bind to specific molecules on the surface of cancer cells and thereby block a signaling pathway required for tumor growth. Today, antibodies can either be used as therapeutic agents on their own or as a tool for transporting cytotoxic or radioactive agents to the tumor cells in a targeted way. An antibody can reliably bind to its antigen on the tumor cell surface and thereby deliver an active substance to the right place inside a human body. In this way, tumor cells can be directly attacked and damaged, forcing them to commit suicide – a process that is called apoptosis.