Following cancer's diagnosis and staging, the clinical oncologist has achieved the necessary condition to elaborate a treatment plan. Cancer treatment usually requires multiple professionals with complementary skills. They should work together in a very well coordinated team. When browsing the following icons, you will better understand the main resources used in cancer treatment and how they are combined in a well-designed treatment plan.
This is the first decision that the physician has to face in cancer treatment. Unfortunately not all tumors are curable. Therefore, the intention of treatment should be defined as curative or palliative. Curative treatments have been very well documented in peer review journal and their indications are clear and precise. The physician should describe the treatment plan, discuss results and risks, making sure the understanding and agreement of the patient. Palliative treatments usually require more complex sharing decision's process. Palliative treatments should combine increasing survival with better quality of life.
Originally, surgery was the only method available for cancer treatment. Large resections have historically been recommended, based on Halstedian principle of radical tumor removal. Local and regional invasion were the most important tumor characteristic, limiting its resectability. Today surgery remains an important resource in cancer treatment. The anatomical knowledge continues to be emphasized by doctors, seeking for proper surgical margins. However, the increasingly use of combined treatments, including both adjuvant chemotherapy and radiation therapy has allowed more conservative and less traumatic resections.
High-energy machines called linear accelerators are used to provide external radiation therapy. The high-energy beams will cause direct damage to the tumor cells DNA and promote the formation of free radicals. The main objective of the post-operative radiation therapy is to reduce tumor local relapse. New techniques are progressively evolving in a more precise definition of treated fields and dose fractionation, reducing toxicity without loss in effectiveness. They include three-dimensional conformal radiation therapy (3DRT) and intensity-modulated radiation therapy (IMRT), allowing more precise and secure treatment field. Currently, surgeons work in combination with radiation oncologists to produce better results with the least damage.
Chemotherapy is as combination of cytotoxic drugs acting on rapidly dividing cells. Historically, it was first used with curative intention in the treatment of lymphomas and leukemia. Later on chemotherapy began to be used in the treatment of other solid tumors, looking for systemic disease control. Cancer is often not restricted to primarily affected organ. Early in tumorigenesis, cancer cells invade lymphatic and blood vessels, leading to distant microscopic deposits called micrometastasis. Unfortunately, micrometastasis are not detectable by imaging methods at cancer diagnosis. In breast cancer, high-risk patients adequately treated with surgery and radiation therapy might later have a systemic relapse if not treated with adjuvant chemotherapy. Ironically, the formation of tumor's lymphatic and blood vessels is an early event in cancer development, often preceding even its clinical detection. The adjuvant chemotherapy concept was developed in order to eradicate all traces of putative residual tumor cells, decreasing the systemic relapse and mortality rate. Based on the same principle, adjuvant hormone therapy acts on micrometastasis, but in more selective hormone-responsive tumors. For instance, it could be used post-operatively to destroy residual breast cancer cells, which express hormone receptors. Chemotherapy and hormone therapy could also be used with neoadjuvant intention. They are used upfront in the treatment of large primary unresectable tumors trying to reduce tumor volume and increase the chance of a complete resection. Both, chemotherapy and hormone therapy might also be used in palliative care. When the disease turns into incurable, these methods are judiciously used for relieving symptoms, increased survival and improving quality of life. Palliative treatments involve difficult technical, ethical and emotional decisions.
Seeking for greater treatment specificity, monoclonal antibodies act on their specific receptors expressed by tumor cells. For example, some types of breast cancer expressing a receptor known as Her2 could be treated with a monoclonal antibody called trastuzumab. Biding trastuzumab with the Her2 receptor, will block downstream signaling pathway, reducing tumor cell proliferation. Rituximab is another monoclonal antibody that binds to the CD20 receptor of B lymphomas, decreasing cell proliferation. Recently, a great number of monoclonal antibodies have been developed, both for curative and palliative cancer treatment. Additionally, a new class of drugs has been developed acting on the immune check points CTLA4 and PD1/PDL1, allowing a better recognition of cancer cells by the patient's immunologic system.