The Newest Technologies to Treat Lung Cancer
Parts 1, 2 and 3 of this series of articles have set the stage for a discussion about the newest approaches to treat lung cancer. Surgery is still the preferred treatment for non-small cell lung cancer (NSCLC), while small cell type lung cancer so easily spreads due to the fragility of the cancer cells that surgery is rarely considered. Complete resection of the tumor, when possible, offers the best assurance of cure and long term survival.
Within the NSCLC category, the decision to treat surgically will depend on whether the patient can stand the surgery and be able, post-surgery, to live a reasonably good life with the remaining lung function after the resection.
The other consideration is the extent of the spread of the tumor; this is when the TNM staging system becomes important. Stages I and II are considered “amenable and responsive to surgical resection.” These are tumor without lymph node involvement (stage I) or with involvement of the lymph nods in the involved lung (stage II). Stage III is when lymph nodes in the chest space between the lungs (mediastinal) are affected. When the mediastinal lymph nodes are on the same side of the involved lung, it’s classified stage IIIA. If they are on the opposite side then it’s classified as stage IIIB. Stage IIIA is also considered to be a candidate for surgical resection.
Chemotherapy post-surgery (called adjuvant chemo) is recommended for all tumors classified as stage II. In addition to chemotherapy, post-surgery radiation therapy is recommended when the excised tumor has cancer cells that extend to the margins of the excised area (called R1) – which “suggests” that every last cell may not have been removed during the resection – and for all stage III lung cancers.
Surgical procedures that may be used to resect lung cancer include:
Lobectomy: This is the surgical resection of a single lobe of the lung. It is the optimal treatment measure because it leaves the other lobes intact and helps to preserve better lung function because there is no disruption of the blood supply. The procedure is done by either opening the chest (open thoracotomy), or by using a solid tube (thoracoscope) inserted between the ribs, guided by video (VATS). This last procedure has the advantage of being minimally invasive. Both approaches require general anesthesia. Tumors located towards the center of the lungs are not amenable to lobectomy.
Limited sublobar (wedge) resection: This is an option for patients who cannot tolerate a full lobe resection because of co-morbid chronic illnesses or advanced age. The procedure is limited to treating tumors that are less than 3 cm. The procedure is done with VATS. The data on long term survival after this procedure is conflicting, but is more favorable for stage I lung cancer
Intra operative brachytherapy: This procedure involves implanting a radioactive seed at the edge of the resected tissue. Its purpose is to decrease the incidence of local cancer recurrence. Initial data on results have been promising. This is especially useful for those with positive tumor margins (R1)
Mediastinal Lymph node dissection: Indicated for those with stage II or III lung cancers, lymph nodes located in various sites in the chest are chosen to be dissected based on samples taken during the surgery via frozen sections. The rate of success depends on the accuracy of the staging of the tumor, and precisely identifying the involved lymph nodes.
The options for radiation therapy include:
Stereotactic body radiation therapy: This technique delivers a number of high radiation dose to a small area by multiple convergent beams. This technique allows for a rapid limiting of the dose at the edges the tumor, which helps to prevent harm to the normal tissue. This is particularly useful for those with advanced COPD.
Conventional radiation therapy: This involves numerous sessions of lower doses of radiation, to a wider area mapped out on the outer chest. This approach is used when the tumor is too large for stereotactic therapy. The potential complications are that radiation alters the white cells contained in the lung’s alveolar sacs and the resulting inflammation can cause scarring and fibrosis of the lungs. This can occur to the uninvolved lung, with consequences presenting up to two years post- treatment.
High dose brachytherapy: This approach is used in cases where the tumor is evident inside the opening of the airways and causing obstruction. A catheter is inserted via bronchoscopy, placed next to the tumor, and then a radioactive seed is presented to the tumor. This approach protects healthy tissue, allowing high doses via precise placement.
Chemotherapy options include:
The most common chemotherapy agents used are Cisplatinum and Carboplatin combined with Taxol or Taxotere. Gemzar (gemzitabine) is a newer agent, and its action, similar to other chemotherapeutic agents is to interfere with the cell division by targeting DNA. Like the other agents, it initially targets cells that divide at faster rates (which can, unfortunately, sometimes include “healthy cells” – a negative side effect).
Specific protocols guide the chemotherapy treatment. A standard course can be administered over one to three weeks and then repeated for a total of six courses, with rest periods in between each course.
While cancer cells are being “killed,” other normal cells are affected and possibly killed resulting in unwanted side effects like anemia, low white blood cell count (impaired immune function), and low platelet count (bleeding issues). Depending on how severe the side effects, chemotherapy may be discontinued.
As mentioned in the earlier columns in this series, the advent of targeted cell therapy has greatly improved patient outcomes.
Overall, the long term survival rate of lung cancer has been a disappointing 10 to 15 percent. This is primarily because 70 percent of patients are diagnosed withadvanced stage III disease. The survival can be as high as 73 percent with stage IA. This data is provided by the largest series in lung cancer, National Cancer Institute’s Surveillance, Epidemiology and End Results (SEER) Program. The keys to improved survival outcomes in lung cancer rest on: - Identification of high risk groups and mitigating the risk factors; - Identification of unique cellular markers in an individual which help to improve formulation of therapy options; - Improved diagnostic and surgical techniques which can be obtained in tertiary centers that can handle a large volume of cases; - Improved identification of unique features of different tumors through special stains and cellular markers; - Specific targeted therapy with new and ever-emerging biological agents.