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Lung cancer represents the most frequent form of
cancer in the United States. It is estimated that in 2005 there will be
170,000 new cases of lung cancer and 160,000 deaths. There are more
deaths from lung cancer in the United States than from cancers of the
breast, colon and prostate combined. Despite years of anti-smoking
campaigns, the incidence of lung cancer continues to rise in females.
The seriousness of lung cancer implies that evaluation and management of
this illness should be carried out at a specialized center.
Pathologists divide lung cancer into two broad
groups: small cell and non-small cell. Small cell lung cancer (SCLC)
accounts for approximately 20% of all lung cancer diagnoses and tends to
grow rapidly and spread to organs beyond the chest. Non-small cell lung
cancer (NSCLC) represents a group of tumors. The four types of NSCLC
include epidermoid cancer (also called squamous cell), adenocarcinoma,
bronchioloalveolar cancer and large cell undifferentiated cancer. The
histologic type of lung cancer determines the therapeutic strategy.
Accurate histologic diagnosis of lung cancer requires an experienced
pathologist.
Lung cancer is further classified according to the
extent of tumor within the body (“stage of disease”). A simplified
staging system for NSCLC includes four groups:
I – cancer confined to the lung with no evidence of
lymph node involvement
II – cancer within the lung and spread to lymph
nodes in the root of the lung
III – cancer within the lung and spread to the
chest wall, lymph nodes in the center of the chest or lymph nodes in the
neck
IV – spread of cancer to organs outside the chest
(bones, liver, brain)
SCLC is divided into two stages:
Limited – cancer within the chest, including lymph
nodes
Extensive – cancer spread to organs outside of the
chest/nodes
Treatment of lung cancer depends upon the stage of
the tumor. Multiple diagnostic tests are necessary to accurately
determine the stage of tumor in an individual patient. These tests
frequently include a computerized tomogram (CT) of the chest, a positron
emission tomogram (PET) of the whole body and surgical inspection of the
lymph nodes within the chest (mediastinoscopy).
Treatment decisions at UCLA for patients with lung
cancer depend upon the evaluation of the patient by a multidisciplinary
team of physicians specializing in thoracic cancer. This team includes
interventional radiologists, pathologists, pulmonologists, surgical
oncologists, medical oncologists and radiation oncologists.
Most stages of lung cancer can benefit from
radiation therapy. Stage I NSCLC is typically treated with surgery
alone. Some patients, however, may not be candidates for definitive
surgery due to the presence of other pulmonary or cardiac conditions.
These patients are usually eligible for primary radiotherapy, often
delivered by highly focused techniques recently adopted at UCLA. Stage
II NSCLC patients typically receive a combination of surgery and
postoperative chemotherapy. Radiotherapy may be used for those with
residual tumor noted after surgery. Stage III NSCLC patients are
frequently not considered surgical candidates. In otherwise healthy
patients, chemotherapy and radiotherapy are utilized simultaneously
(“concurrent chemoradiotherapy”). If patients are elderly or have other
serious medical conditions, chemotherapy preceeds the course of
radiotherapy (“sequential chemoradiotherapy”). Occasionally, stage III
patients may undergo a course of radiotherapy prior to attempted surgery
(“preoperative therapy”) or after a surgical removal of tumor bulk
(“postoperative therapy”). Stage IV patients can benefit from palliative
radiotherapy to control symptoms due to disseminated cancer.
Limited stage SCLC is treated with chemotherapy as
definitive therapy since surgery is rarely performed for this type of
lung cancer. Limited stage patients may also receive protective
irradiation of the brain to prevent the later appearance of central
nervous system metastases. Extensive stage SCLC patients may benefit
from palliative radiotherapy to control symptoms due to disseminated
cancer.
In the UCLA Department of Radiation Oncology,
patients are seen by a radiation oncologist to discuss the indications
for radiotherapy, the individual plan of treatment and the potential
side effects. Patients then undergo a session called “simulation” to
accurately establish the portion of the body to be irradiated. This
session often requires a special CT of the chest performed in the
department. The information obtained from this CT is used by medical
physicists to precisely map the radiotherapy dose throughout the chest
prior to delivering any treatment. Subsequent treatment typically begins
3-5 days after the simulation. Treatment is given every weekday,
Monday-Friday. Patients are in the department no more than 15 minutes
per day. Radiotherapy treatments are painless and similar to undergoing
a chest X-ray. Side effects during the course of radiotherapy typically
occur after 2-3 weeks of treatment and include difficulty swallowing,
skin redness, fatique. Side effects may also occur several weeks or
months after completion of treatment and include inflammation of the
irradiated lung (“radiation pneumonitis”). Proper attention to the
details of radiotherapy treatment planning reduce the incidence and
severity of complications and represent a major reason for undergoing
radiotherapy at a specialized center such as UCLA. During the course of
radiotherapy, patients and their family meet at least weekly with the
radiation oncologist to assess progress and manage any side effects. The
Department of Radiation Oncology has nurses specialized in management of
radiotherapy side effects and a social worker to provide assistance in
transportation and housing issues.
The typical course of radiotherapy for the primary
treatment of NSCLC involves 35 visits to the radiation oncology clinic.
Patients treated preoperatively receive 25 treatments and those treated
postoperatively receive 28 treatments. Selected patients with Stage I
inoperable NSCLC may receive an innovative focused form of intense
radiotherapy called “stereotactic irradiation”. This type of treatment
typically involves only 3-5 visits but is restricted to tumors 5
centimeters or less in size (see Figure 1). Limited stage SCLC patients
typically receive 31 treatments to the chest and 15 to the brain.
Patients with Stage IV NSCLC or extensive SCLC receive 10-20 palliative
treatments depending upon the site being treated.
Patients receiving radiotherapy for lung cancer at
UCLA have at their service the full range of state-of-the-art
technology: virtual simulation, CT-based conformal treatment planning
(Figure 2 a-c), intensity modulated treatment planning (IMRT),
stereotactic irradiation using a dedicated linear accelerator and
multileaf field shaping (see Figure 3).
Figure 1. Dose distribution from stereotactic
radiotherapy of early stage NSCLC. Pink represents 90% of the applied
dose, green 50% and purple 30%.
Figure 2 (a) axial, (b) coronal and (c) sagittal
display of conformal dose distribution for treatment of lung cancer.
Figure 3 Radiotherapy field, in heavy green,
achieved by multileaf shaping for the treatment of lung cancer in light
green and pink.
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