According to World Health Organization (WHO), in 2008, 7.6 million people died from cancer, representing 13% of all deaths occurring in the world that year. On a global scale, there are presently 24.6 million cases of cancer and around 10.9 million new cases are registered each year.
Studies have shown that the number of cancer cases will increase by 70% by 2030 in developed countries and by 90% in developing countries. The number of cancers such as breast cancer, prostate cancer, and colorectal cancer will see a rise, while cervical cancer and cancers of the stomach will be less likely to infect humans than they do now.
The most common types of cancer currently affecting developing countries are cervical cancer, stomach cancer, liver cancer, and Kaposi’s sarcoma. In developed countries, there is a rising number of patients with lung cancer, breast cancer, prostate cancer and colorectal cancer.
Given all the cited statistics, the diagnosis of “cancer” should sound like a death sentence to many people. Nowadays, however, science took a big step forward. There are new methods for early diagnosis of the disease and new effective methods of treatment.
In general, there are multiple treatment methods to be used in cancer patients. Traditional methods of treating solid cancer tumors include surgery, radiation therapy, chemotherapy, and several other methods (Table 1). Surgery and radiation therapy are local treatments methods, as the tumor is either directly removed or irradiated to destroy the cancerous cells constituting it. Chemotherapy, in its turn, represents a systemic method of treatment.
|Technique||Invasive method, by which the tumor is cut out||Ideal for tumors which do not invade other parts of the body||Usually lasts one day. Often combined with chemotherapy and radiation therapy|
|Application||Low doses of radiation are delivered in the affected area, also known as teletherapy||Tumors in any part of the body||Usually once a day for 2 to 9 weeks|
|Treatment duration||Cancer destruction drugs are administered in the form of tablets, injections or intravenously||Cancer of any localization||From one to several days or continuously|
Table 1. Traditional methods of cancer treatment.
The surgical intervention affords complete removal of tumors and of areas where tumors might have spread (i.e. regional lymph nodes, apparently normal tissues surrounding a tumor). Surgical treatment, however, does not always lead to healing. The reason is the remaining in the body of some tumor cells which cannot be identified and removed by surgery (micrometastases), carrying the risk of neoplasm recurrence. In order to reduce the recurrence risk and to improve the prognosis of inoperable patients, two other treatment modalities were introduced, namely radiotherapy and chemotherapy. Their essence lies in the fact that cells with a high division rate (such as tumor cells) are more sensitive to radiation and cytotoxic agents as compared to normal cells (with a lower division rate). Radiotherapy uses ionizing radiation for destruction of tumor cells. It is performed after a surgery for “sterilizing” the tumor and prior to surgery for reducing the local recurrence risk; for decreasing the tumor’s volume and for increasing chances to obtain a complete tumor resection, or as the main therapeutic modality in inoperable patients. Even so, radiotherapy is not useful for destruction of micrometastases distant from the primary tumor site. For this purpose we use chemotherapy, implying the administration of substances that preferentially destroy tumor cells. The drugs enter the bloodstream and are distributed throughout the entire body, thus being effective in eradicating micrometastatic foci after surgery. This therapeutic intervention may also be performed before surgery for the same reasons as radiotherapy.
Besides these traditional therapeutic options, other new treatment methods are explored (Table 2).
Hormone therapy is used for certain cancer types (e.g. breast cancer) to decrease the recurrence risk after surgery or to extend and increase the quality of life in patients with unresectable tumors.
Specific inhibitors method consists in the action of certain drugs on specific proteins and processes, which are mainly localized in cancer cells. Inhibition of these processes prevents the growth and division of cancer cells.
Antibodies treatment is based on the administration of antibodies to attack tumor cells, by different mechanisms: either depriving the cancer cells of necessary signals or causing cell death. Because of their specificity, antibodies can be assigned to specific inhibitors.
Immunotherapy is based on the stimulation of the patient’s immune system so that the antitumor response intensity is increased.
One of the newest treatments for cancer is the Cyber Knife technique, which is a perfect replacement for surgical treatment. The method consists in the exact directing of gamma rays upon the tumor. After 4 or 5 sessions, the tumor is completely destroyed, with no need for anesthesia and surgery, and with no damage to the healthy tissue surrounding the cancer. Furthermore, this method is effective for removing metastases in internal organs.
An important place in the treatment of cancer is held by the brachytherapy technique. This method is based on the introduction of Iodine -132 radioisotope into the tumor with the use of a fine needle, acting a source of radiation that eventually destroys the tumor.
Experimental cancer treatment methods are new and not yet fully tested therapies emerging in the process of scientific and clinical research and experiments, and are not yet included in the therapeutic standards adopted by the WHO (Fig. 1).
High-intensity focused ultrasound (HIFU) represents tumor destruction with high-energy focused ultrasound.
Gene therapy is designed for people who are genetically predisposed to malignant tumors. It consists in the introduction of genes into the tumor, which causes cell death or prevents cancerous cells from multiplying.
Cryoablation is a local freezing and tissue devitalisation process, which allows creating a necrosis zone of precise shape and size for the destruction of affected tissues and of adjacent healthy cells.
Local hyperthermia implies a session of heating the tumor tissue up to a temperature that causes cell death. Hyperthermia sessions require special equipment.
Angiostatic drugs are drugs that interfere with the formation of the capillaries in tumors, after which the tumor cells are killed as a consequence of nutrient access denial.
Laser therapy is a method based on the transformation of a laser beam’s light energy into heat: the temperature reaches up to 60 °C for a few seconds, thus rapidly inducing cell death.
Anaerobic bacteria used to destroy the tumor’s central part not penetrated by drugs, is another method currently under research. It is already well-known that the tumor’s periphery is destroyed by chemotherapy.
Therapeutic vaccination against cancer cells can treat several types of existing cancers, such as cervical cancer (caused by Human Papilloma Virus) or liver cancers (caused by Hepatitis B Virus).
Nanotherapy is the introduction into the human body of nanorobots that either deliver the medicine to the desired site, or attack the malignant tumor and its metastases. It may also be used for long-time monitoring.
Neutron Capture Therapy consists of the administration of special non-radioactive drugs which selectively accumulate in cancerous tumors. The tumor is subsequently irradiated with a low neutron radiation. The medications actively react to such radiation and multiply its intensity inside of the tumor itself. As a result, the cancer cells are destroyed. In this case, the total radiation doses the patient receives are much lower than with conventional radiotherapy.
|New methods of cancer treatment||Experimental methods of cancer treatment|
High-intensity focused ultrasound (HIFU)
Table 2. New and experimental methods of cancer treatment.
Considering the wide variety of cancer treatment methods, their application to patients depends on factors such as tumor type, location and stage of development, as well as patients’ general state of health and their financial possibilities. After all, each patient’s treatment is on an individual basis. Cancer treatment requires careful selection of one or more interventions, such as surgery, radiotherapy and chemotherapy. The aim is the patients’ recovery or prolongation and improvement of their quality of life. Cancer diagnosis and treatment must be mandatorily complemented by psychological support. At this stage, the best results in cancer treatment are observed when using the combined methods (surgery, radiotherapy and chemotherapy). Detection of cancer in its early stages of development tends to lead to full patient recovery under the influence of adequate treatment. Thus, with all traditional, new and experimental methods for treatment of this disease, specialists can firmly assert that curing cancer is now possible in many cases.