Women with vulval cancer that has spread to the groin lymph nodes need additional treatment. The standard treatment usually involves surgical removal of as many groin nodes as possible (known as complete inguinofemoral lymphadenectomy (IFL)). However, only about 30% of women with vulval cancer in whom lymph nodes are not obviously enlarged will have groin involvement; therefore, in about 70% of these women additional surgery is not necessary. As groin surgery often causes later swelling of the legs and other unpleasant side effects, it would be preferable not to undergo the surgery if it is not required; therefore, accurate screening tests to determine who should have surgery are needed.
Sentinel node assessment involves identifying the main lymph node/s draining the tumour. After the main (sentinel) nodes are identified, they are removed and examined under a microscope to check for cancer cells. Additional surgery depends on the findings of the examination: if cancer cells are found in the nodes, additional surgery is necessary; if the nodes are cancer-free, additional surgery can be avoided.
Why is this review important?
Several studies have been done using dyes or traceable agents to identify sentinel nodes. From these studies, it is not clear whether all of these agents are sufficiently accurate to predict which women have cancerous spread to the groin. This review summarises the evidence and produces overall estimates of the relative accuracies of the available tests.
How was the review conducted?
We included all studies that tested the accuracy of tracer agent/s against the standard method of identifying cancer in the groin nodes (removing all groin nodes (IFL) and examining them under a microscope). Women in these studies had vulval cancer of Federation of Gynecology and Obstetrics (FIGO) stage IB or higher without obvious signs of cancer in the groin (enlarged or palpable nodes). We only included studies of at least 10 women, and noted any concerns about the quality of studies.
What are the findings?
We included 34 studies (1614 women) that evaluated three techniques: blue dye only, technetium (a radioactive substance) only, or blue dye and technetium combined. Ten studies used all three techniques during the course of the study (one technique per participant). There are two attributes to a test: the ability to identify or detect the sentinel node, and the ability to identify the cancer in the sentinel node. We found that all tests can identify cancer in the groin nodes with good accuracy (more than 90% of nodes with cancer will be accurately identified with any of the tests), although the combined test was the most accurate (95%). The ability of the tests to detect sentinel nodes varied, with the blue dye test only detecting sentinel nodes in 82% of women, compared with 98% for the combined test. If sentinel nodes are not detected, they cannot be examined for cancer cells; therefore, women in whom sentinel nodes are not detected will usually need to undergo IFL.
What does this mean?
The combined and technetium only tests are able to predict accurately which women have cancerous spread to the groin. For a group of 100 women undergoing assessment, the findings mean that approximately one or fewer women having the combined or technetium only tests will undergo an unnecessary IFL, compared with approximately 11 women having the blue dye only test. This is mainly because the blue dye only test is not as good as technetium in identifying sentinel nodes. Fewer women with spread to the groin will be missed with the combined or technetium only tests (1 to 3 out of 30) compared with the blue dye only test (1 to 8 out of 30). It is not clear whether women with negative sentinel nodes (i.e. no spread of cancer to the groin lymph nodes) who do not undergo IFL will live as long as those who undergo IFL. The current best data on survival come from a Dutch study that followed up 259 women with negative sentinel nodes and reported a three-year survival of 97%.