2. Tumour size and axillary lymph node status are the most important
prognostic factors in potentially curable carcinoma of the breast.
Physical examination, radiologic imaging of the axilla or prognostic
models based on primary tumour characteristics cannot accurately predict
the occurrence of axillary metastases1-2. Hence axillary lymph node
dissection is an important staging procedure in the surgical treatment of
breast cancer.
National Institute of Health Consensus recommended a level I and II
axillary lymph node dissection for staging and regional control of breast
cancer 3 . To minimize the short and long term morbidity associated with
axillary lymph node dissection, some investigators have proposed a
limited axillary dissection 4 . This procedure has less morbidity but misses
24% to 42% of axillary metastases (5-6).
Selective axillary dissection means that one should be able to select the
patients with breast cancer for total axillary dissection from the ones that
don’t need total axillary clearance. This means that if the axilla is involved,
it should be completely cleared of all nodal tissues as both the number
and level of involved nodes have important prognostic value. Similarly if
the axillary nodes are not involved they should be left untouched to avoid
3. the morbidity of total axillary dissection.
There is general agreement that total lymphadenectomy is indicated in
patients with clinical suspicious nodes or pathologically proved
metastases to the regional lymph nodes. A major controversy exists
regarding the utility of this procedure for patients with clinical stage I (CS-
I) disease because most of these patients are without nodal metastases
and therefore can derive no benefit from regional lymph adenectomy.
% of cases where axillary nodes were involved.
T1 Tumours 11.3% positive cases
T2 Tumours 28.3%
T3 Tumours 42.8%
Since breast cancer is being detected at early stage due to screening
procedures the chances of axillary nodes being free of cancer are high
and hence the need for selection of axillary dissection.
Selection is possible if we can prove that a single axillary node (Sentinel
node) initially receives malignant cells from a breast carcinoma and that
an uninvolved sentinel node reliably forecasts a disease free axilla.
4. This concept of sentinel node biopsy in carcinoma breast is not new.
Oliver cope referred to the Delphian node in 1963 as the lymph node that
will “fortell the nature of a disease process” affecting a nearby organ.
That the predicting value of the first level node is considerable was
shown by Veronesi etall7 in a study of 539 patients with carcinoma of the
breast treated with total axillary dissection and with positive axillary
nodes. Only in 1.5% of the cases the first level was skipped by
metastases and in 0.4% of cases both first and second levels were
missed.
They also showed that axillary lymph node metastases occur in an orderly
fashion and that predictive value of first level is considerable i.e. when first
level nodes are clear chances of 2nd and 3rd level involvement is rare.
When first level lymph nodes are involved, chances of metastases being
present at higher levels is high. Of the first level nodes – if one can detect
the first or the lymph node nearest the site of primary carcinoma (called
sentinel lymph node) its pathological status can be reliably used to
selectively dissect or not to dissect the whole axilla.
The validity of this concept was first demonstrated for melanoma over 10
years ago by Morton & colleagues8. Patent blue V dye was injected close
5. to the primary lesion and the blue stained sentinel node was later found
by dissection. Various dyes have been tested to optimise the kinetics both
in terms of take up and transport and retention by the first node to receive
that lymph. Blue dyes have been used to identify the sentinel node in
breast cancer, either alone or in conjunction with other radioactive
materials.
In 1996, John J. Albertini et al9 carried out a study to identify the sentinel
lymph node by intra operative lymphatic mapping using a combination of
a vital blue dye and filtered technitium – labelled sulfur colloid. The
sentinel lymph node was identified and removed followed by a definitive
cancer operation and complete axillary dissection.
Their results indicated that SLN was successfully identified in 92% of
patients using the two lymphatic mapping procedures. 32% were found to
have metastatic disease and SLN was tested positive in all 32% of
patients.
Turner etall10 from Joyce Eisenberg Keefer Breast Centre, at Santa
Monica, California used 3 to 5 ml. of 1% isosulfan blue vital dye into the
breast parenchyma surrounding the primary tumor. Sentinel node was
recognised in the axillae, removed and then level I & II were also
6. dissected. Sentinel nodes were examined by H&E and I.H.C. (Immuno
histochemistry). Where sentinel nodes were free by H&E and I.C.H. all
nonsentinel nodes were examined by I.H.C. only one sentinel node
negative patient was positive by I.H.C. from non sentinel nodal mass. In
addition 14.3% of sentinel nodes that were negative by H&E stain were
tested positive with I.H.C.
Umberto Veronesi etall11 from European Institute of Oncology in 163
women with operable breast cancer injected microcolloidal particles of
human serum albumin labelled with technitium– 99m. This tracer was
injected subdermally close to the tumor site on the day before surgery and
scintigraphic images of breast and axille were taken at 10,30 mins. and 3
hrs. later. A mark was placed over the site where radioactive node
existed. A small Ɣ- ray detector probe was used at surgery to locate the
sentinel node and made possible its removal through a small separate
axillary incision. Complete axillary dissection was then carried out. The
results show that they could accurately predict axillary lymph node status
in 97.5% of the patients in whom sentinel node was identified. In 38% of
the cases with metastatic axillary nodes, the sentinel node, was the only
positive node
7. Hence from the ongoing studies
· It is possible to dissect sentinel nodes with the help of vital blue
dyes and or lympho scintigraphy. There are advantages and
disadvantages of vital dyes and lympohscintigraphy. Vital blue dye can be
injected few minutes before surgery while lympohscintigraphy must be
carried out at least 2 hours before surgery.
Disadvantage of dye method is that axillary tissue must be dissected
blindly until the blue node is located and this can be few cms. away from
the skin incision. The advantage of hand held probe is that it locates the
node and indicates exactly where the skin incision should be made and
guides the dissection, which is quite successful.
·Sentinel node is a reliable good predictor of the axillary nodal status.
·Frozen section facilities and multiple sectioning of sentinel node is a
must, if second operation is to be avoided.
· Immunohistochemistry and PCR enhances the detection of
micrometastatis. Micrometastatis is also a prognostic factor as of today.
· Extensive microcalcification or multifocality is a contraindication to the
injection method because in such cases sentinel nodes may be falsely
8. negative.
· Another advantage of sentinel node dissection is its use in Neo adjuvant
therapy in Carcinoma breast.
·It provides the pathologists only 1-2 nodes to perform a more detailed
and focussed examination and possibly PCR analysis, serial sectioning
for immunohistochemical staining.
There is a word of caution. Before sentinel node biopsy is adopted
routinely in breast cancer management, the outcome of several clinical
trials that are presently comparing survival in patients staged by this new
approach with that of patients receiving traditional axillary management
should be awaited. There is also a learning curve in dissecting sentinel
node and hence for the first few cases both sentinel lymph nodes and
complete axillary clearance be carried out in individual hands and
reliability tested.
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