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The Current Role of Sentinel Lymph Node Biopsy in Breast, Melanoma, and Gastrointestinal Cancer
Since that initial report, multiple investigators have confirmed the accuracy
Table 2: Prospective Multi-institutional Trials of Sentinel Lymph
and reliability of the technique in patients with invasive breast cancer.
27–30
As
Node Biopsy in Patients with Colon Cancer
was also the case with malignant melanoma, numerous studies have shown
a complementary role for the use of pre-operative lymphatic mapping and
Investigator Number of Patients False-negative Rate (%) Upstaging* (%)
intraoperative localization with radiolabeled pharmaceuticals. However,
Bertagnolli
38
72 54 1.2
Bilchik
39
132 7 23.6
unlike malignant melanoma, lymphatic drainage of the breast is predictable
Bembenek
40
315 46 21
enough that the use of blue dye alone is sufficient in the majority of cases
Stojadinovic
41
82 10 10.7
should that be the surgeon’s preference.
Lim
42
120 41
The role of SLNB in patients with early invasive breast cancer seems
*Sentinel node initially deemed tumor-negative by hematoxylin and eosin (H and E) staining
but interpreted as tumor-positive after use of ultra-staging techniques (multisectioning,
broadly accepted. Patients with clinical stage I or II disease in the absence immunohistochemistry [IHC], and/or reverse transcriptase-polymerase chain reaction [RT-PCR]).
of clinically evident nodal metastasis have a 20–30% risk for occult nodal
disease, and therefore are reasonable candidates for surgical nodal Although DCIS represents pre-invasive malignant change, studies have
staging, particularly when one considers the effect of increasingly demonstrated a 1–2% rate of occult nodal metastasis. While this risk was
effective systemic therapies in this disease.
31
Few would argue that SLNB not substantial enough to warrant routine ALND in the pre-SLNB era, the
has emerged as the nodal staging procedure of choice for patients with availability of the SN technique has lessened concerns about excessive
early invasive breast cancer, given not only the dramatic decrease in morbidity. In addition, many patients with DCIS are currently diagnosed via
morbidity compared with conventional nodal dissection but also the image-guided biopsy, which results in a higher risk for upstaging to invasive
ability of pathologists to more accurately detect small deposits of cancer disease when the primary tumor is completely excised. However, those
when able to focus on select nodes. Growing evidence suggests that patients treated with breast conservation can undergo successful SLNB after
status of the SN has prognostic implications, even for patients with very upstaging at a second operation in most instances. Clearly, the majority of
small or microscopic metastatic disease.
32,33
patients with DCIS diagnosed by core needle biopsy need not be offered
SLNB routinely. Instead, a selective approach is warranted in patients with
Current matters of debate regarding the use of SLNB in breast cancer center higher risk for invasive disease, such as those with a palpable mass, high
largely on its role in patients with locally advanced disease or those with nuclear grade, possible microinvasion, or a large radiographic area of
ductal carcinoma in situ (DCIS). Large, bulky tumors often preclude the disease.
35
Patients undergoing mastectomy for DCIS should also be strongly
routine use of breast conservation in patients with breast cancer. Instead, considered for SLNB given the high risk for discovering invasive disease in
these patients may often undergo neoadjuvant systemic therapy with the the mastectomy specimen and the inability to reliably perform selective
hope of shrinking the primary tumor enough to allow for successful nodal sampling afterwards, especially in the setting of immediate
segmental mastectomy. Given the effectiveness of this approach in achieving reconstruction using free flaps.
breast conservation, it is no surprise that nodal status often changes during
the course of therapy. Many believe that, in order to be accurate, the SN Gastrointestinal Malignancies
technique must be applied prior to the initiation of systemic therapy in these
patients.
34
This translates into additional cost and morbidity as patients Colon Cancer
ultimately have to undergo two operative procedures. Furthermore, the The successful use of the SN technique in the surgical management of
benefit of SLNB is somewhat diminished, as a higher percentage of these patients with malignant melanoma and breast cancer has led clinicians to
widely investigate the role of SLNB in other malignancies, most notably
colorectal cancer (CRC). The rationale for the use of SLNB in patients
Sentinel lymph node biopsy has
undergoing resection for CRC is based on the way in which nodal status
determines which patients are selected for adjuvant systemic therapy.
radically transformed the surgical
Growing evidence suggests that a substantial percentage of pathologically
management of breast cancer and
node-negative stage I and II patients treated with conventional segmental
mesenteric resection and nodal analysis are actually understaged and thereby
malignant melanoma and is now routine
denied important and increasingly effective systemic therapy. Recurrence
in the care of these patients.
rates in node-negative patients as high as 25% support this notion.
36
In 1998, our group described the application of the SLNB concept to a
patients will have a tumor-positive node in the pre-operative setting and will variety of solid malignancies, including CRC.
3
A prospective follow-up study
require a completion dissection. Although evidence for strong in 2000 that focused on gastrointestinal malignancies included 50 patients
recommendations regarding the role of SLNB in the setting of planned with CRC and demonstrated the manner in which in vivo SLNB could alter
neoadjuvant chemotherapy is lacking, some national guidelines recommend the extent of surgical resection.
37
In that same year, Saha et al. reported their
pre-therapy SLNB and post-therapy CLND if the SN is tumor-positive, experience with 86 patients diagnosed with localized CRC. SNs were
independent of tumor response to systematic therapy.
25
Others have found identified in 85 of 86 patients.
6
In the 56 patients with a tumor-negative SN,
SLNB accurate and helpful after neoadjuvant chemotherapy, because SLNB correctly predicted the remainder of the nodal dissection in 94% of
prognosis is determined by post-treatment nodal staging. The common use cases. In 15 of 29 node-positive patients, the SN was the only site of nodal
of adjuvant radiotherapy further complicates the issue. metastasis and seven had micrometastasis only in the node. These findings
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