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Radiation for Non
Small Cell Lung Cancer
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Radiation for Non
Small Cell Lung Cancer
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| Surgery is generally the treatment of choice
for patients with non-small-cell lung cancer, radiation alone may cure 25-73% of
the patients with Stage I or II, but for patients with more advanced cancer (Stage III)
radiation alone probably cures only 6% and combined radiation/chemotherapy only
8 - 17% (up to 29% with higher doses.) In patients who have a complete surgical
resection, there is no role for routine radiation for patients with N0 or N1 disease, but
probable benefits for those with N2 (mediastinal nodes) with increases in the
survival from 22%/4y to 43%.
A recent study added a
radiosensitizer to radiation/chemo (RSR 13 or efaproxiral) and increased survival from
12.5 months up to 20.6 months. A study in stage IIIA (N2) found that
chemo-radiation was as good as chemo-radiation followed by surgery (go
here). A study from UNC (LCCC9603) using Carbo/Taxol and higher dose XRT of 74Gy in IIIA/IIIB reported better results with median survival of 24 months and 29%/5 years. Common survival with higher dose 3D conformal is shown below |
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Treatment recommendations for patients with NSCLC should be made after joint consultation and/or discussion by a multidisciplinary team including surgical, radiation, medical oncologists and pulmonologists. The overall plan of treatment as well as needed imaging studies should be determined before any non-emergency treatment is initiated.
Radiation therapy should be offered as potentially curative treatment to patients with Stage I and II NSCLC who are medically inoperable but of reasonable performance status and life expectancy. In patients receiving radiation therapy or chemoradiation with curative intent, treatment interruptions or dose reductions for temporary and manageable toxicities should be avoided. Such situations include but are not limited to Grade 3 esophagitis and hematologic toxicities. Careful patient monitoring and aggressive supportive care are preferable to treatment breaks in potentially curable patients. It is often helpful to explain this philosophy to patients prior to the onset of toxicities.
If the resection margin is negative and mediastinal nodes are positive, adjuvant chemotherapy will be given for 3 cycles followed by postoperative radiotherapy. If the resection margin is positive, postoperative radiotherapy will be given first followed by adjuvant chemotherapy.
In patients receiving postoperative radiation therapy because of involved mediastinal nodes or resection margins which are close or positive, discussion with the thoracic surgeon and pathologist is helpful in designing appropriate target volumes. Treatment planning should be based on CT scans obtained in treatment position. IV contrast should be given for better target and critical organ delineation whenever possible. In patients who are to receive induction chemotherapy prior to beginning radiation or chemoradiation, consideration should be given to obtaining a baseline planning CT prior to starting induction chemotherapy.
Cobalt and orthovoltage beams are not appropriate for curative treatment. There are increasing data that lack of electronic equilibrium at lung/tumor interfaces can lead to significant underdosing, particularly of small tumors or tumor extensions, and that this problem increases with higher beam energy. It may thus be preferable to avoid high-energy photons and instead use lower energies (4-10 MV) in most patients. High energy photons (15MeV, 18MeV, etc) may be preferable when used to treat larger GTV’s (gross tumor volumes) surrounded by consolidated and/or atelectic lung tissue, bulky lymphadenopathy or large blood vessels, thus achieving a better dose distribution and also an improved therapeutic ratio.
