|
|
|
| From OncoLog, March 2013, Vol. 58, No. 3 |
|
|
Advances in Pulmonary Medicine Facilitate Cancer Diagnosis, Treatment
By Sarah Bronson
 |
 |
| Bronchoscopic images show a tumor obstructing the right main bronchus (top) and the same bronchus after tumor debulking (bottom). |
The
lungs present unique challenges in cancer diagnosis and
treatment—navigating a maze of bronchi to find and sample tissue that
will lead to an accurate diagnosis of lung cancer, for example, or
deciding whether to proceed with treatment for cancer in the presence
of concomitant lung disease.
For these reasons, pulmonologists play an important role in the care of
cancer patients. “We help diagnose lung cancer, diagnose and alleviate
lung complications associated with cancer and cancer treatment, and
optimize respiratory status so patients can undergo treatment safely,”
said Rodolfo Morice, M.D., a professor in the Department of Pulmonary
Medicine and chief of the Section of Interventional Pulmonology at The
University of Texas MD Anderson Cancer Center.
Suspected lung cancer necessitates accurate diagnostic procedures and
proper consideration of the lungs’ susceptibility to complications. And
if cancer is present, lung function should, ideally, be optimized and
conditions such as pleural effusions and pneumonia cured before cancer
treatment begins. Sensitive, minimally invasive bronchoscopies and
up-to-date management of lung disease can help ensure that cancer
treatments are as effective as possible.
Increasing the diagnostic yield of bronchoscopy
Imaging modalities such as radiography often provide the first
indication of lung cancer, but only by directly examining the tissue
that had suspicious radiographic findings can a cancer diagnosis be
made or ruled out. Techniques for sampling lung lesions and mediastinal
lymph nodes vary in accuracy, reach, and invasiveness. The choice
between an invasive diagnostic procedure such as mediastinoscopy and a
less invasive procedure such as bronchoscopy depends on the location of
the target, the size and hence the visibility of the target, and the
patient’s ability to tolerate the potential complications from these
procedures.
Previously, opting for a less invasive biopsy often meant sacrificing
accuracy. But with the use of endobronchial ultrasonography (EBUS),
“navigation” bronchoscopy, and autofluorescence bronchoscopy, sites of
suspected lung cancer can be more accurately targeted without
subjecting patients to open surgical biopsy or transthoracic needle
biopsy and to increased risks such as pneumothorax, which occurs in up
to 30% of patients who undergo transthoracic needle biopsies.
EBUS
Conventional white-light bronchoscopy illuminates only the inside of
the airway and can sample lymph nodes based on their locations relative
to endobronchial landmarks; the procedure has a diagnostic yield of
only 30%–50%. Adding an ultrasonography probe to the end of a
bronchoscope reveals the lymph nodes near the trachea and main bronchi
as far as 5 cm beyond the bronchial walls, increasing the diagnostic
yield to about 95%. Using the airway as a passage, EBUS can sample the
high mediastinal, paratracheal, subcarinal, and hilar lymph nodes,
reaching farther into the peribronchial tissues than mediastinoscopy,
which cannot access the hilar lymph nodes.
Adding ultrasonography to bronchoscopy, already a relatively safe
procedure, introduces little risk; EBUS is associated with the same
infrequent complications and contraindications as conventional
bronchoscopy.
Navigation bronchoscopy
Navigation bronchoscopy tracks and maps the bronchoscope’s position in
real time within a three-dimensional rendering of the airways based on
recently acquired computed tomography data. The end of a sampling
catheter is equipped with an electromagnetic position sensor that
disturbs a magnetic field encompassing the patient’s lungs and thus can
be pinpointed within that field or, alternatively, with a sensor that
emits electrical signals indicating its position. The sensor is placed
at key points selected during the planning phase. Each of these points
within the actual airways is then mapped to the corresponding point in
the digital rendering, and the real-time view and the digital rendering
are merged. Thus, physicians can navigate the bronchi using not only
the immediate white-light view of the airways but also a detailed map
that is integrated with the computed tomography images.
 |
 |
 |
| Bronchoscopic images using white light (top), autofluorescence (center), and narrow-band imaging (bottom) show a squamous cell carcinoma (arrows) in the lower trachea. |
Navigation bronchoscopy can go much farther into the lung than EBUS,
entering not only the trachea and mainstem bronchi but also branches as
peripheral as fifth-generation bronchi 2 mm wide. Navigation
bronchoscopy facilitates the bronchoscopist’s ability to sample
peripheral pulmonary lesions and complements the role of EBUS for
sampling mediastinal and hilar lymph nodes, allowing for a complete
diagnostic workup and nodal staging of lung cancer with a single
intervention.
Autofluorescence bronchoscopy
Autofluorescence bronchoscopy uses blue light together with white light
to detect changes in the airway that portend cancer, and this technique
can direct biopsies of premalignant tissue and carcinoma in situ before
the disease becomes evident on noninvasive imaging or with white light
bronchoscopy alone.
To produce autofluorescence, a bronchoscope’s light is filtered to a
wavelength of about 400–450 nm; this blue light causes normal chemical
compounds in the airways to reflect largely green light and
premalignant tissue to reflect largely red light. Unlike other
fluorescence methods that require a photosensitizing compound,
autofluorescence requires only light. Autofluorescence bronchoscopy may
be most useful in patients at high risk of airway cancer and lung
cancer patients who received radiation therapy for positive margins
after resection.
Although adding blue light to conventional bronchoscopy increases the
sensitivity of the bronchoscopy, particularly for detecting high-grade
lesions, this technique may also increase the rate of false-positive
findings. Because autofluorescence may reveal a large number of areas
that look abnormal but may not all be malignant, another modality
called narrowband imaging often is used in conjunction with
autofluorescence bronchoscopy to select the locations that are most
likely to contain malignant tissue. Specific wavelengths of blue and
green light that are absorbed by hemoglobin reveal hidden blood
vessels; a disorganized, tortuous vasculature suggests malignancy.
Lesions with suspicious vasculature in addition to abnormal
fluorescence can then be biopsied.
Managing lung conditions concomitant with cancer
Conditions affecting the lungs—such as toxicity due to previous
treatments, chronic obstructive pulmonary disease, pleural effusions,
and pneumonia—can limit cancer treatment and decrease quality of life.
Often, these comorbidities must be dealt with and respiratory function
improved so that patients can begin or continue cancer treatment.
George Eapen, M.D., an associate professor in the Department of
Pulmonary Medicine, said, “We help patients feel better so that going
into treatment, they have the best shot possible at a successful
outcome.”
Pleural effusions, particularly those that recur after thoracentesis,
can be a persistent hindrance to cancer treatment readiness. A useful
method for managing recurring pleural effusions is the indwelling
catheter, which is tunneled under the skin and inserted into the
effusion site. The catheter keeps the space between the pleura dry and
allows the formation of adhesions to seal the space, eventually
preventing fluid from reaccumulating. Previously, patients with such
effusions were hospitalized and treated with sclerosing agents or
repeated thoracentesis; now these patients can drain the fluid at home
and achieve effective symptom resolution. Allowing patients to drain
their own effusions also gives them and their families a greater sense
of involvement in their care. “The catheter allows patients to
reestablish control over their bodies. That sense of empowerment is
very important in maintaining their psychological well-being,” Dr.
Eapen said.
Another lung comorbidity that commonly occurs with cancer and may
hinder treatment is pneumonia, one of the top causes of death in
patients with lung cancer or leukemia. Suspected pneumonia presents
several diagnostic and treatment challenges: distinguishing
inflammation due to a condition such as chemotherapy toxicity from a
disease caused by a pathogen; deducing whether a pathogen is a virus,
bacterium, or fungus; identifying within these pathogenic categories
the particular strain of pneumonia, which will often be a strain that
does not typically affect people without cancer; and selecting an
effective treatment without subjecting the patient to side effects that
may disrupt his or her cancer treatment.
An experimental technique being studied for identifying the organisms
responsible for pneumonia is to perform whole-genome microarray
analysis on lung cells from the affected patient (often acquired using
bronchoalveolar lavage). Preclinical studies show that pathogens
elicit specific host gene expression responses that can clarify the
cause of pneumonia when other tests are not sufficient. There is hope
that this or similar methods could prove clinically useful in the
future for diagnosis of pneumonia.
 |
| Endobronchial ultrasonography shows a subaortic lymph node (dotted line). |
In addition to treating specific comorbidities, pulmonologists help
prepare patients for cancer treatment by improving the patients’
cardiopulmonary function. Some patients can improve their performance
status through carefully titrated rehabilitation, i.e., an exercise
program tailored to their particular needs. These programs aim to
increase patients’ cardiopulmonary functional capacity and thus their
ability to tolerate treatment and their quality of life regardless of
whether further treatment is planned.
Sometimes all it takes to determine that a patient with less-than-ideal
lung function is ready for a tough treatment is better information.
Assessments prior to surgeries such as lung resection or lobectomy have
become more comprehensive in recent years, examining not just
individual parts of the body but what an entire person can tolerate.
Lung, heart, and muscle function can be assessed individually, but
broader assessments such as exercise tests show what those systems can
achieve in coordination, enabling more accurate predictions of
postoperative function. And it turns out that these more accurate
predictions often result in more patients receiving treatment. “Of the
patients who would traditionally be deemed ineligible for surgery or
other treatment on the basis of lung function alone, as many as one
third are actually eligible according to the more complete assessment,”
said Dr. Morice.
Patients who lack the cardiopulmonary functional capacity to endure
curative treatment for their cancer still can be made more comfortable,
and patients who cough up blood or struggle to breathe can be given
immediate relief. Interventional procedures performed through a
bronchoscope can clear the airway of tumors, cauterize bleeding, and
place stents to keep airways open. Dr. Eapen said that one of the most
valuable services he provides is simply helping patients with
obstructed airways or compressed lungs breathe well again. “We can’t
always cure, but we can ease patients’ concerns about suffocating and
relieve their suffering,” he said.
Pulmonary medicine has been continually gaining and refining tools to
guide biopsies of lung disease, manage conditions affecting the lungs,
and improve patients’ quality of life. Dr. Morice expressed the hope
that pulmonologists and oncologists throughout the medical community
can maintain a dialogue and share expertise and perspectives.
For more
information, contact Dr. George Eapen at 713-563-4256 or Dr. Rodolfo Morice at 713-563-4257.
Other
articles in OncoLog, March 2013 issue:
 TOP
Home/Current Issue | Previous Issues
| Articles by
Topic | Patient
Education
About Oncolog | Contact OncoLog | Sign
Up for E-mail Alerts
©2013 The University of
Texas MD Anderson Cancer Center
1515 Holcombe Blvd., Houston, TX 77030
1-877-MDA-6789 (USA) / 1-713-792-3245
Patient
Referral Legal Statements Privacy
Policy
|
