In some instances, patients present with growth of lung cancer on the inside of the airways (endobronchial).  For example, a tumor is growing inside the wall of the trachea or the bronchi.  When this occurs, patients often have symptoms like shortness of breath or persistent cough.  This situation can occur when patients have disease in their lung or even when this is the only site of disease.  The diagnosis is usually made by a pulmonologist who performs a direct visualization of the airways by bronchoscopy.  These nodules are missed on CT scans frequently because even when the block most of the airway –they are actually still quite small.  Here’s a representative view of an endobronchial lesion:

 (Click to enlarge)

   This type of tumor position is perfectly suited for a treatment approach called endobronchial high dose rate (HDR) brachytherapy.     This treatment approach utilizes a radioactive seed that is placed directly in contact with the tumor.  The length of contact and time of contact are determined by the size of the tumor and its location.  High dose rate refers to the use of a very hot radioactive seed that is usually made out of iridium.  The seed is attached to the end of a wire.  A very specialized machine houses the radioactive seed and wire.  It can then be programmed to feed the wire out of the machine and into the catheter for a predetermined length and time.  High dose rate procedures have basically replaced low dose rate procedures because the radiation dose can be delivered in a period of minutes rather than days if one used low dose radioactive sources. 

   The procedure involves the coordination of a pulmonologist and a radiation oncologist.  The pulmonologist will usually identify the tumor in the airway and help place a catheter down the nose and into the airway.  The catheter usually runs from the tumor location back out of the airways through the nose.  The radiation oncologist will then feed a the radioactive seed down this catheter to the site of the tumor and treat the tumor.

   The time of treatment is usually around 5-7 minutes.  The patient has some discomfort from the catheter that is in their nose, back of throat and in their airways.  They usually feel a little “tickle” and want to cough.  We usually give people some numbing medicine and anti cough medicine during the procedure.  The catheter can be removed immediately after the treatment is completed.  The treatment can be done once or repeated once a week over several weeks.  The number of treatments can be variable and may depend on the response of the tumor and/or its initial size.

   If the tumor is on the outside of the airway and compressing on the airway from the outside, this procedure is typically not used.  The reason is that endobronchial HDR treatments only penetrate 5mm to 1cm.  There is a rapid fall off in dose.  So they are perfectly suited for treating something in close proximity that isn’t very thick.   Here’s a favorable outcome from a representative case:

   This treatment has been used for decades.  Success occurs if people breath better after treatment.  This almost always occurs and only rarely is their local tumor progression after this treatment.

   Alternatives to this type of treatment include surgery, photodynamic therapy (PDT), external beam radiotherapy, and laser.  Not all of these alternatives are always available or amenable to a particular tumor location.

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