Due to the ability of cancer cells to multiply fast and evade natural senescence and death mechanisms, they bear a growth advantage over healthy cells. They can pass through blood and lymphatic vessels and tend to spread. If untreated, most cancers eventually infiltrate important organs, such as the liver, lungs, or brain, and this may lead to death. However, the advances in cancer treatment have resulted in dramatically increased cancer survival with many patients being cured of or living with controlled cancer.
Cancer treatment goals
Depending on the type, location, aggressiveness, genetic features of cancer, the stage at which it was diagnosed, and the patient’s health state, several approaches may be applied to cancer treatment.
When cancer is diagnosed at early stages, most often the goal is to cure cancer. This means that after the treatment no evidence of disease as assessed by laboratory tests, biopsies, or scans is expected. A curative approach may not be feasible in aggressive cancers (e.g., pancreatic, gallbladder, esophageal cancer) or in less aggressive cancers diagnosed at advanced stages. In this case, the goal is to control cancer and prolong the patient’s survival ensuring the highest possible quality of life.
In cases when there is little or no prospect of a cure, the primary goal of cancer treatment is to optimize the quality of life through palliative care which includes managing pain and stress, emotional support, social services and help with necessary resources/equipment.
Another option for people with cancer, even at its advanced stages, is to participate in a clinical study (trial). While all efforts are made to ensure the safety of the patient in a clinical study, the clinical benefit may or may not be apparent. The main purpose of the clinical study is to gain knowledge about the drug and not to treat the patient.
Types of cancer treatment
For some cancers, based on the low risk of their progression weighted against the treatment side effects, treatment may be delayed as the cancer is monitored over time (this is called active surveillance). This approach is used for some less aggressive blood cancers and low-risk prostate cancer.
Surgery is usually done when a tumor is located in one area of the body and has not spread. The tumor may be removed in whole or, if this is not possible, partially, which allows other treatments to work more efficiently. Also, surgery may improve such symptoms as pain or organ dysfunction because of tumor pressure. Surgery options include conventional open surgery, laparoscopic surgery, laser surgery, robotic surgery, surgery using heat or cold to destroy cancer, etc. Sometimes, surgery is the only type of treatment needed to cure cancer, e.g., in the case of early-stage skin cancer called melanoma.
Chemotherapy employs drugs that kill cancer cells. Several types of chemotherapy drugs act by distinct mechanisms hampering the cancer cell replication process.
Similarly, in radiotherapy, radiation induces breaks in cancer cells’ DNA molecules which makes replication impossible, and the cell eventually dies. Radiation may be administered externally by radiotherapy machines (e.g., linear accelerators) or the source of radiation (wires, rods, or seeds) may be implanted in the area affected by cancer or near it - this type of radiotherapy is called brachytherapy.
Targeted therapy includes medicines that act on specific mutated gene regions or proteins that are present in cancer but not in healthy cells. Drugs used in molecular targeted therapy are classified into small molecules, monoclonal antibodies, immunotherapeutic cancer vaccines, and gene therapy. A classic example of targeted therapy is imatinib (Gleevec) which has revolutionized the treatment of blood cancer called chronic myeloid leukemia. Imatinib blocks the activity of an enzyme called tyrosine kinase, dysregulation of which results in increased survival and growth of cancer cells.
Immunotherapy encompasses the treatments that help a patient’s immune system find and kill cancer cells, i.e., immune checkpoint inhibitors, cell therapies, monoclonal antibodies, oncolytic virus therapies, and cancer vaccines. Some treatments such as monoclonal antibodies may be classified both as targeted therapy and immunotherapy.
Hormonal therapy is used in such types of cancer (prostate or breast cancer) that need certain hormones for their growth. For instance, the drug called tamoxifen blocks estrogen receptors on breast cancer cells thereby preventing the treated cancer from coming back.
Bone marrow (stem cell) transplantation is used to treat certain blood cancers and other cancers where bone marrow cells have been destroyed by intensive cancer treatments.
How are the most appropriate treatments chosen?
When patients are diagnosed with cancer, they are offered so-called “first-line” therapy. This may be a combination of surgery, chemotherapy, and radiotherapy, and in certain cancers targeted therapy may be administered first-line. First-line therapy is based on a pooled analysis of numerous clinical studies and is supported by the guidelines of professional organizations such as the American Society of Clinical Oncology (ASCO) or the National Comprehensive Cancer Network (NCCN).
If first-line cancer treatment fails or stops working, or if the side effects are too burdensome, the patients may receive second-line treatment. Second-line treatment alternatives often include targeted therapy or immunotherapy. Some patients may need third and subsequent lines of therapy.
How long does cancer treatment last?
The duration of cancer treatment varies a lot. In some early-stage cancers, such as melanoma, uterine cancer, or cancer of a large intestine, surgery may be the only type of therapy needed. If required, chemotherapy or radiotherapy is initiated within 5-12 weeks after surgery. The total dose of radiation is administered in divided doses (fractions) for up to 10 weeks. Chemotherapy is administered in cycles and lasts up to 6 months. When cancer is advanced, maintenance therapy that lasts up to several years may be advised. With targeted or hormone therapy, lifelong treatment may be needed.
Cancer treatment statistics in the US
Advances in cancer treatment have resulted in increased cancer survival rates. For instance, among cancer survivors, more than half live without cancer for ten years, and almost one-fifth for more than 20 years.
Cancer treatments and survival rates for the most common cancers are provided in a Table below.
| Cancer type | Treatments | 5-year survival rate |
|---|---|---|
| Breast cancer | Stage I or II: breast-conserving surgery plus radiotherapy or mastectomy Stage III: mastectomy plus chemotherapy Stage IV: radiotherapy, chemotherapy Hormone-receptor-positive cancer: hormonal therapy plus other therapiesHER2-positive cancer: chemotherapy plus immunotherapy | Overall, 90% for patients diagnosed from 2011 through 2017 Stage I: 100% Stage IV: 28% |
| Colorectal cancer | Stage I and II: surgery without chemotherapy Stage III: surgery plus chemotherapy Stage IV: surgery plus chemotherapy and/or radiotherapy Inoperable stage IV: chemotherapy, observation Metastatic cancer with specific biologic features: targeted therapy | Overall, 65% for patients diagnosed from 2011 through 2017 Rectal cancer: 67% Colon cancer: 64% Stage I: >90% Stage IV: 11% (colon) and 15% (rectal) |
| Acute myeloid leukemia | Chemotherapy, immunotherapy, targeted therapy, stem cell transplantation Promyelocytic type: all-trans-retinoic acid | Children and adolescents: 69% 20 to 49 years: 58% 50 to 64 years: 35% 65 years and older: 9% |
| Chronic myeloid leukemia | Targeted therapy, chemotherapy, stem cell transplantation in resistant cases | 71% for those diagnosed between 2011 through 2017 |
| Acute lymphoblastic leukemia | Chemotherapy, targeted therapy, stem cell transplantation, immunotherapy including CAR-T cells | Children and adolescents: 89% 20 years and older: 40% |
| Chronic lymphocytic leukemia | Active surveillance, chemotherapy, immunotherapy, targeted therapy, radiotherapy, splenectomy, CAR T-cell immunotherapy | 87% |
| Hodgkin‘s lymphoma | Classical type: chemotherapy, radiotherapy, stem cell transplantation, targeted therapy Early stage of nodular lymphocyte predominant type: radiotherapy Advanced stage of nodular lymphocyte predominant type: chemotherapy plus radiotherapy, immunotherapy | Overall: 88% Classical: 87% Nodular lymphocyte predominant type: 96% |
| Non-Hodgkin‘s lymphoma | Chemotherapy plus immunotherapy with or without radiotherapy | 64-90% |
| Lung and bronchial cancer | Surgery, chemotherapy, radiotherapy, targeted therapy, immunotherapy | Overall, 22% for those diagnosed from 2011 through 2017 Stage I: 65% Stage IV: 5% Non-small cell lung cancer: 26% Small cell lung cancer: 7% |
| Melanoma | Stage I: surgery Stage III: surgery plus immunotherapy Stage IV: immunotherapy, targeted therapy | Stage I: 100% Stage IV: 34% (3-year survival) |
| Prostate cancer | Active surveillance, hormone therapy, chemotherapy, bone-directed therapy, radiotherapy | 98% for those diagnosed from 2011 through 2017 Non-metastatic: 100% Metastatic: 31% |
| Testicular cancer | Stage I: surgery Stage II: surgery plus chemotherapy or radiotherapy | Overall: 95% Metastatic: 75% Seminoma: 90% Other types: 94-98% |
| Thyroid cancer | Surgery (total or partial resection), radiotherapy (radioactive iodine) Metastatic or aggressive disease: targeted therapy | Overall: 98% Medullary and anaplastic carcinoma: 90% Anaplastic carcinoma: 7% |
| Urinary bladder cancer | Stage I or II: surgery (trans-urethral resection of bladder tumor) with or without local chemotherapy, biological therapy, radiotherapy Stage III: surgery (removal of bladder) with or without chemotherapy and/or radiotherapy, immunotherapy | Overall: 77% Stage 0: 96% Stage IV: 14% |
| Uterine (endometrial) cancer | Stage I: surgery Stage II: surgery alone or plus radiotherapy Stage III: surgery and chemotherapy with or without radiotherapy | Overall: 81% Stage I: 95% |
Key takeaways
Cancer is a heterogeneous group of diseases; there are many approaches to cancer treatment which may include surgery, chemotherapy, radiotherapy, targeted therapy, immunotherapy, and hormone therapy.
Due to cancer‘s ability to develop resistance mechanisms, initial (first-line) treatment may stop working. In this case, a different treatment is proposed (second and subsequent lines).
The treatment duration varies a lot in different types of cancer: from the time needed to heal from surgery to several months, several years, or life-long therapy.
The success of the treatment expressed as a 5-year survival rate in different types of cancer varies from several percent (e.g., small cell lung cancer) to almost a hundred percent (e.g., stage I breast, prostate cancer, or melanoma).
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