Modalities of treatment in cancer
Various modalities are available for the treatment of cancer.
Often, modalities are combined based on patient and tumor characteristics.
Surgery
Biopsy - Diagnostic - Therapeutic - palliative - used alone or in combination
Alone / in combination
The size, type, and location of the primary tumor may determine operability and outcome.
Metastases - Radical operations avoided. Aim at only reduction of tumour mass.
Factors increasing operative risks :-
Age,
Comorbid conditions
Debilitation due to cancer & poor nutrition due to anorexia and the catabolic influences of tumor growth,
Primary tumor resection (if no metastasis) with adequate margins (as in breast cancer surgery)
Removal of involved regional lymph nodes, adjacent organ, or en bloc resection.
When the primary tumor has spread into adjacent normal tissues extensively, surgery may be delayed so that other modalities (eg, chemotherapy, radiation therapy) can be used to reduce the size of the required resection.
Resection of metastases may be done.
Cytoreduction operations are done (reduction of the bulk)
Palliative surgery - Surgery to relieve symptoms and preserve quality of life
Reconstructive surgery
Radiation Therapy
Radiation therapy alone
Radiation therapy plus surgery (for head and neck, laryngeal, or uterine cancer)
Radiation with chemotherapy and surgery (for sarcomas or breast, esophageal, lung, or rectal cancers) improves cure rates and allows for more limited surgery .
Radiation for palliation when cure is not possible:
For brain tumors: Prolongs patient functioning and prevents neurologic complications
For cancers that compress the spinal cord: Prevents progression of neurologic deficits
For superior vena cava syndromes: Relieves venous obstruction
For painful bone lesions: Usually relieves symptoms
Types of radiation therapy
External beam radiation with photons (gamma radiation), electrons, or protons
Gamma radiation using a linear accelerator
Brachytherapy involves placement of radioactive seeds into the tumor bed itself (eg, in the prostate or cervix).
Stereotactic radiation therapy is radiosurgery with precise stereotactic localization of a tumor
Systemic radioactive isotopes - iodine-131 - thyroid cancer
Factors to be considered
Nature of the delivered radiation (mode, timing, volume, dose)
Properties of the tumor (cell cycle phase, oxygenation, molecular properties, inherent sensitivity to radiation)
Treatment timing (critical)
Dose fractionation (critical)
Target volume
Configuration of radiation beams
Dose distribution
Modality and energy most suited to the patient’s situation
Radiation therapy sessions begin with the precise positioning of the patient.
large daily doses given over 3 wk for palliative treatment or smaller doses given once/day 5 days/wk for 6 to 8 wk for curative treatment.
Adverse effects
Lethargy
Fatigue
Mucositis
Dermatologic manifestations (erythema, pruritus, desquamation)
Esophagitis
Pneumonitis
Hepatitis
GI symptoms (nausea, vomiting, diarrhea, tenesmus)
Chemotherapy
Alkylating agents : busulfan, carboplatin, chlorambucil, cisplatin, cyclophosphamide, dacarbazine, melphalan, nitrogen mustard, thiotepa
Antimetabolites : cytarabine, 5-fluorouracil (5-FU), methotrexate
Antitumor antibiotics : dactinomycin, daunorubicin, doxorubicin (Adriamycin), mitomycin
Plant alkaloids : etoposide, vinblastin, vincristine, paclitaxel
Hormonal therapy
Hormonal therapy uses hormone agonists or antagonists to influence the course of cancer. It may be used alone or in combination with other treatment modalities.
Hormonal therapy is particularly useful in prostate cancer, which grows in response to androgens. Other cancers with hormone receptors on their cells (eg, breast, endometrium) can often be palliated by hormone antagonist therapy or hormone ablation
Androgens and antiandrogens
Estrogens and antiestrogens - Tamoxifen in breast cancer
Progestins and antiprogestins
Luteinizing hormone-releasing hormone analogs
Steroids - Prednisolone
More commonly, multidrug regimens
Multidrug regimens typically are given as repetitive cycles - The interval between cycles should be the shortest one that allows for recovery of normal tissue.
Continuous infusion may increase cell kill with some cell cycle–specific drugs (eg, 5-fluorouracil).
Immunosuppression
Many of the drugs used for cancer suppress the immune system
Bone Marrow/Stem Cell Transplantation
Bone marrow or stem cell transplantation is an important component of the treatment of otherwise refractory lymphomas, leukemias, and multiple myeloma (for an in-depth discussion of this topic, see Hematopoietic Stem Cell Transplantation).
Gene Therapy
Genetic modulation is under intense investigation. Strategies include the use of antisense therapy, systemic viral vector transfection, DNA injection into tumors, genetic modulation of resected tumor cells to increase their immunogenicity, and alteration of immune cells to enhance their antitumor response.
Vaccines
Vaccines designed to trigger or enhance immune system response to cancer cells
sipuleucel-T, an autologous dendritic cell–derived immunotherapy - in patients with metastatic prostate cancer.
Monoclonal antibodies
Monoclonal antibodies directed against unique tumor antigens.
Trastuzumab, an antibody directed against a protein called HER-2 or ErbB-2, plus chemotherapy has shown benefit in metastatic breast cancer that expressed HER-2.
Adjuvant therapy
Systemic chemotherapy or radiation therapy given to eradicate residual occult tumor after initial surgery.
Neoadjuvant therapy
Chemotherapy, radiation therapy, or both given before surgical resection
To enhance resectability and preserve local organ function.
Histologically positive nodes turn to negative
Diagnosis and assessment of reponse to treatment
Imaging (eg, CT, MRI, PET) is frequently done after 2 to 3 cycles of therapy to evaluate response to treatment
