The damage and/or removal of lymph nodes is a common side-effect of cancer diagnosis and treatment. This can result in the insufficient clearance of lymphatic fluid, and manifestation of a chronic swelling condition known as lymphedema. So what can be done about this? “Direct” surgical reconstruction methods are being explored that involve modifying the remaining healthy lymphatic vessels to bypass the lymphatic block caused by the damaged/missing lymph nodes. These methods have met with some limited success (read our blog post on lymphatic surgery). An alternative “indirect” approach has been proposed that involves replacing the damaged lymph nodes altogether with an autologous transplant of healthy lymph nodes from elsewhere in the patient’s own body. But does this approach solve one problem by creating another?
With approximately 600 lymph nodes in the human body, there may be areas of sufficient excess functional capacity that lymph node removal would not be detrimental under most normal circumstances. One promising lymph node transplantation approach being investigated for treating breast cancer-related lymphedema involves transplanting lymph nodes from the groin region into the armpit region. The current view is that this procedure shows some promise for partially relieving lymphedema, and importantly, that the development of secondary lymphedema in lower limbs does not appear as a side-effect. New research published this month (Viitanen, T.P., Seppanen M.P., et al. Plast Reconstr Surg. 2012 Epub Aug 8) studied the effects of this procedure on the donor site specifically.
The authors performed lymphatic groin flap transfers on 13 patients with lymphedema and then measured lymphatic function at the donor site limb for 8 to 56 months using limb circumference measurements as well as lymphoscintigraphy. Whereas limb circumference measurements can identify the presence of swelling, lymphoscintigraphy allows researchers to observe fluid flow directly in the vessels by injecting a small radioactive tracer dye.
As was expected, the authors did not observe donor site limb lymphedema in their patients over the time period studied. However, contrary to current opinion that groin flap lymph nodes are not critical for lymph drainage of the lower limbs, the authors did observe slower lymphatic fluid flow in the donor site limb in 6 of the 10 patients that consented to lymphoscintigraphy, 2 of which had what was considered to be “somewhat abnormal” lymph transport. While the clinical relevance of these changes remains unclear, the authors argue that this data should serve as a warning that such surgeries should be “performed as conservatively as possible to avoid any undesirable effects to the donor area”.
Unfortunately, unlike with kidney transplants, there may not be enough excess capacity built into the lymphatic system to enable lymph node transplantation without a significant risk of detrimental effects on the donor site. Hopefully this study will help spur further research into the development of artificial lymph nodes, an interesting area of research currently being investigated by researchers including our own Dr. Miles Johnston at the Sunnybrook Research Institute in Toronto.