There some patients with early stage lung cancer that are not good candidates for standard lung surgery because of their underlying poor lung function. A standard lung surgery typically involves removing the entire lobe of the lung that contains the cancer. Unfortunately, for some patients with underlying COPD or emphysema – they can’t afford to lose a complete lobe of the their lung. In this situation, some surgeons have performed more limited surgery including doing a “sub-lobar” resection. The results for patients who have this limited surgical resection are not nearly as good as patients that have a complete lobectomy. In some series, the incidence of local recurrence can be as high as 20-40% if only a limited surgery is performed. The problem with these limited surgeries is that the surgeon often leaves microscopic disease behind along the edges of the surgical specimen. In other tumor types, the surgical margins are evaluated carefully and more tissue is often resected if the margins are involved. In lung cancer, evaluation the margins from the surgery specimen is more difficult, and the incidence of additional microscopic cells left in the area around the resection is probably quite high. This probably explains while the recurrence rate for small tumors is quite low with a conventional lobectomy, and much higher when less tissue is removed in a sub-lobar resection.
Brachytherapy means the use of locally placed radiation. In this case, radioactive seeds are placed in and around the surgical suture line after the surgery is complete. These seeds are sewed into the lung tissue or sewed into a mesh fabric that is then placed on the lung in the area that is at highest risk.
Below is a model with seeds, and then CT image of the radiation to a region in the patient being modeled:
The seeds are left there permanently. They deliver a small dose of radiation just in the vicinity of the where they are placed. Early studies have suggested that the placement of these seeds after a sublobar resection can considerably reduce the risk of recurrence of lung cancer. There doesn’t appear to be many side effects experienced by the patient who undergoes this procedure, so overall it appears relatively safe. There are some specific radiation precautions that must be taken. Studies have looked at lung function following the brachytherapy, and the brachytherapy doesn’t appear to reduce lung function.
There is an open study which is randomly allocating patients to a sub-lobar resection or a sub-lobar resection plus brachytherapy. It is hoped that this study will convincingly answer the question of whether this procedure reduces the risk of recurrence.