Lymphatic mapping in solid neoplasms: state of the art

Sentinel lymphatic mapping among women with early-stage cervical cancer: A systematic review

The presence of pelvic lymph node metastases is without doubt the most significant prognostic factor that determines recurrences and survival of women with early-stage cervical cancer. To avoid the underdiagnosis of lymph node metastasis, pelvic lymphadenectomy procedure is routinely performed with radical hysterectomy procedure. However, the pelvic lymphadenectomy procedure may not be necessary in most of these women due to the relatively low incidence of pelvic lymph node metastasis. The removal of large numbers of pelvic lymph nodes could also render non-metastatic irreversible damages for these women, including vessel, nerve, or ureteral injuries; formation of lymphocysts; and lymphedema. Over the past decades, the concept of sentinel lymph node biopsy has emerged as a popular and widespread surgical technique for the evaluation of the pelvic lymph node status in gynecologic malignancies. The histological status of sentinel lymph node should be representative for all other lymph nodes in the regional drainage area. If metastasis is non-existent in the sentinel lymph node, the likelihood of metastatic spread in the remaining regional lymph nodes is very low. Further lymphadenectomy is therefore not necessary for a patient with negative sentinel lymph nodes. Since the uterine cervix has several lymphatic drainage pathways, it is a challenging task to assess the distribution pattern of sentinel lymph nodes in women with early-stage cervical cancer. This review article will adapt the methodology proposed in these studies to systematically review sentinel lymphatic mapping among women with early-stage cervical cancer.

The role of ultrasound in the detection of cervical lymph node metastases in clinically N0 squamous cell carcinoma of the head and neck

Nodal involvement is the most important prognostic factor in head and neck squamous cell carcinoma (HNSCC) of mucosal origin. The presence of a single ipsilateral or contralateral metastatic node reduces survival by 50% and bilateral disease by a further 50%. The management of N+ HNSCC is relatively clear-cut. By contrast, the investigation and treatment of patients with clinically N0 disease is controversial. Most institutions electively treat the neck with surgery or radiotherapy because the risk of occult metastases is over 20%, even though it will be unnecessary in the majority of cases. In this situation the main purpose of staging would be to assess those nodes that are not going to be removed. However, the optimal management of the clinically N0 neck remains controversial and there is growing interest in a more conservative approach. Research is now directed toward finding a method of staging sensitive enough to bring the risk of occult metastases below 20%. High spatial resolution, ease of multiplanar scanning, power Doppler and the ability to perform guided fine-needle aspiration for cytology give ultrasound (US) an advantage over other imaging techniques.

Contrast-assisted ultrasound for sentinel lymph node detection in spontaneously arising canine head and neck tumors

OBJECTIVES

We sought to evaluate a minimally invasive contrast-assisted ultrasound (US) technique for sentinel lymph node (SLN) localization.

METHODS

Microbubble contrast medium was injected into peritumoral tissues in 10 dogs with spontaneous head or neck tumors. Regional lymph nodes (LNs) were imaged up to 20 minutes after contrast administration using power Doppler US. Comparative lymphoscintigraphy studies were performed in all dogs by peritumoral injection of 99mTc-sulfur colloid administered around the primary lesion.

RESULTS

US contrast enhancement of SLN revealed sentinel nodes and associated lymphatics in 8 of 10 dogs. In each instance in which contrast-enhanced LN was identified with US, a corresponding SLN was detected by lymphoscintigraphy. Multiple SLNs were present in 2 dogs. Regional lymph nodes were positive for metastasis in 1 dog and reactive in 9 dogs.

CONCLUSIONS

Contrast-assisted US is effective in localizing SLN. This technique could reduce or eliminate many of the limitations of current SLN detection procedures.

Selective sentinel lymphadenectomy for malignant melanoma, Merkel cell carcinoma, and squamous cell carcinoma

To date, selective sentinel lymphadenectomy (SSL) should be considered a standard approach for staging patients with primary invasive melanoma greater than or equal to 1 mm. It is imperative that the multidisciplinary team master the techniques of preoperative lymphoscintigraphy, intraoperative lymphatic mapping, and postoperative pathologic evaluation of the sentinel lymph nodes (SLNs). An SLN is defined as a blue, "hot" and any subsequent lymph node greater than 10% of the ex vivo count of the hottest lymph node. Any enlarged or indurated lymph node in the nodal basin should be excised. Frozen sections are not recommended. For extremity melanoma, delayed SSL may be performed. Preoperative lymphoscintigraphy for extremity melanoma may be done the night before so that the surgery can be scheduled as the first case of the following day. Every surgeon who uses blue dye should be aware of the potential adverse reaction to isosulfan blue and treatment for such a potential fatal reaction. A complete lymph node dissection is done if the SLN is found to be positive. Elective lymph node dissection (ELND) should not be done if an SSL can be performed as a staging procedure. SSL has further been applied to stage the nodal basin for Merkel cell carcinoma and high-risk squamous cell carcinoma. It is important for investigators involved with the SSL to follow the clinical outcome of these patients, so that the role of SSL can be further defined.

Dynamic MR lymphangiography and carbon dye for sentinel lymph node detection: A solution for sentinel lymph node biopsy in mucosal head and neck cancer

BACKGROUND

The practical application of sentinel lymph node biopsy in squamous cell carcinoma of the head and neck is restricted by the time sensitivity of blue dye and lack of spatial resolution and nonspecific node enhancement with radiocolloid. This study evaluates the use of magnetic resonance (MR) lymphangiography and carbon dye labeling to circumvent these limitations.

METHODS

Gadomer/carbon dye mixture was injected into the tongue and stifle of adult swine (n = 4). MR lymphatic mapping was followed by intraoperative mapping with isosulfan blue dye. Sentinel lymph node biopsy and completion node dissection were performed 60 minutes after injection in four nodal basins and at 7 days after injection in eight.

RESULTS

The technique was successful in all 12 nodal basins. The sentinel lymph nodes were stained black at the time of the immediate and delayed dissections.

CONCLUSIONS

MR lymphangiography provides temporal and anatomic localization of the sentinel lymph node with a single investigation. Carbon dye is a sensitive and persistent visual marker of MRI-targeted sentinel lymph nodes.

The use of sentinel lymph nodes in gynaecological malignancies

PURPOSE OF REVIEW

Lymphatic mapping and sentinel node biopsy represent one of the most revolutionary advances in oncological surgery in recent years. In this review, the current state of sentinel node detection in gynaecological cancers and its use in vulvar and cervical cancer are assessed.

RECENT FINDINGS

Since the recent clinical application of sentinel node biopsy for melanomas and breast cancer, there has been extensive research on the implementation of this technique to most solid neoplasias. Studies on the feasibility of sentinel node biopsy in vulvar cancer have shown that the status of the sentinel node is an accurate predictor of the status of inguinal nodes. The clinical implementation of the procedure requires validation and is under investigation. In the last two years, several pilot studies on the feasibility of lymphatic mapping/sentinel node biopsy in cervical cancer have yielded promising results. There is minimal experience of its use in endometrial cancer. Detailed pathological study of a sentinel node biopsy with ultrastaging and immunohistochemical or polymerase chain reaction analyses can identify lymph node micrometastasis that conventional methods would identify as negative for metastatic disease. The best histopathological procedure for sentinel node biopsy, the clinical significance of micrometastases, and the appropriate management of such micrometastases are currently under investigation.

SUMMARY

Sentinel node biopsy is one of the main research interests in gynaecological oncological surgery. At present there are not enough data to permit modification of current treatment protocols. Large and multi-institutional trials are required in order to define the implementation of sentinel node biopsy in clinical practice with the objective of achieving safer and more conservative surgery.

Laparoscopic sentinel node mapping in early-stage cervical cancer

OBJECTIVE

We aimed to determine the feasibility and accuracy of sentinel node (SN) mapping and its ability to predict the status of the regional nodal basin.

METHODS

From October 2000 to September 2002, 70 patients undergoing radical surgery for early-stage cervical cancer (stage IA, IB, and IIA) were offered lymph node mapping for identification of the sentinel node. All patients underwent SN identification laparoscopically followed by a complete laparoscopic pelvic node and parametrial dissection. The SN mapping was done after intracervical blue dye injection in all cases and was combined with preoperative lymphoscintigraphy following intracervical Tc-99 injection and intraoperative SN detection with a miniaturized laparoscopic gamma probe in 29 cases (42%).

RESULTS

The blue dye technique alone (n = 70) identified at least 1 SN in 61 (87%) of the patients. The rate of SN detection by side of dissection was 74%, 70% on the left side and 77% on the right side. Bilateral SN were identified in 60% of cases. In the subgroup of patients who had the combined technique (n = 29), the rate of SN detection increased from 79 to 93% (P = 0.04). The bilateral SN detection rate increased from 55 to 72% when adding lymphoscintigraphy (P = 0.03). In the last 15 cases of the series, the SN detection rate reached 93% (14/15) and this was statistically significant compared to the detection rate of the first 55 cases (P < 0.01). A total of 135 SN were identified, with the majority (88%) being located at three main sites: the external iliac, obturator, and bifurcation. Thirty-six patients (51%) had 2 SN identified, and 16 (24%) had 3 SN or more. Twelve (17%) patients had positive lymph nodes. In those cases, the rate of SN detection per side of dissection in patients with normal appearing nodes at laparoscopy was 75%, whereas it was only 56% in patients with macroscopically involved lymph nodes (P = NS). The false negative rate was 0. The negative predictive value of SN mapping was 100% and the sensitivity was 93% with the combined technique. Two patients had allergic reactions to the blue dye (3%).

CONCLUSION

Sentinel node mapping with the combined blue dye technique and lymphoscintigraphy in patients with cervical cancer is laparoscopically feasible and is highly accurate. The detection rate improves significantly with experience and with the use of lymphoscintigraphy.

Clear cell sarcoma in the era of sentinel lymph node mapping

Clear cell sarcoma of the tendons and aponeuroses (CCSTA) are rare aggressive soft tissue tumors with tendency for lymph nodes dissemination. Lymph node involvement is a correlate for prognosis. We present three patients with CCSTA in whom simultaneous sentinel lymph biopsy (SLNB) and resection was performed. Sentinel lymph node mapping may have a role in clear cell sarcoma from a prognostic standpoint. Further investigations are needed for validation.

Sentinel lymph node biopsy in head and neck cancer

In the past decade, the technique of sentinel lymph node biopsy (SLNB) has been applied to a vast array of primary neoplasms, ranging from head and neck melanoma to vulvar carcinoma. At present, experience with SLNB is greatest in patients with melanoma and breast cancer. In view of the well known complications associated with cervical node dissection, it has been suspected for some time that cervical SLNB, if successful, might reduce the morbidity associated with the definitive care of patients with head and neck cancers. This report assesses the current status of SLNB in the treatment of head and neck cancers; while formal investigations of the efficacy of this technique are recommended, SLNB has not yet been demonstrated to possess the same level of utility seen in SLNB in melanoma and breast cancer patients. As a consequence, the application of SLNB to head and neck cancers remains an experimental technique--one which has not yet acquired the status of the standard of patient care.

Nodal staging of colorectal carcinomas and sentinel nodes

This review surveys the staging systems used for the classification of colorectal carcinomas, including the TNM system, and focuses on the assessment of the nodal stage of the disease. It reviews the quantitative requirements for a regional metastatic work up, and some qualitative features of lymph nodes that may help in the selection of positive and negative lymph nodes. Identification of the sentinel lymph nodes (those lymph nodes that have direct drainage from the primary tumour site) is one such qualitative feature that is claimed to allow the upstaging of colorectal carcinomas via an oriented, enhanced pathological work up. Current evidence in favour of a change in the requisite of assessing as may lymph nodes as is possible, and concentrating the efforts on only a selected number of lymph nodes, is weak.

Selective sentinel lymphadenectomy for malignant melanoma

To date, selective sentinel lymphadenectomy (SSL) should be considered a standard approach for staging patients with primary invasive melanoma greater than or equal to 1 mm. It is imperative that the multidisciplinary team master the techniques of preoperative lymphoscintigraphy, intraoperative lymphatic mapping, and postoperative pathologic evaluation of the sentinel lymph nodes (SLNs). A SLN is defined as a blue, "hot", or any subsequent lymph node greater than 10% of the in vivo count of the hottest lymph node and as an enlarged or indurated lymph node. Frozen sections are not recommended. For extremity melanoma, delayed SSL may be performed. Preoperative lymphoscintigraphy for extremity melanoma may be done the night before so that surgery can be scheduled as the first case of the following day. Every surgeon who uses blue dye should be cognizant of the potential adverse reaction to isosulfan blue and treatment for such a potential fatal reaction. A complete lymph node dissection is done if the SLN is found to be positive. Elective lymph node dissection should not be done if SSL can be done as a staging procedure. It is important for investigators involved with SSL to follow the clinical outcome of their patients so that the role of SSL can be further defined.

Sentinel lymph node versus axillary lymph node dissection for early-stage breast carcinoma: a comparison using a utility-adjusted number needed to treat analysis

BACKGROUND

The current study was performed to compare the value of sentinel lymph node dissection (SND) and axillary lymph node dissection (AND) in improving the utility-adjusted survival for early-stage breast carcinoma patients.

METHODS

A number needed to treat (NNT) analysis was used to compare SND with AND. In the NNT equation, 1/(S(SND) - S(AND)), S is the 5-year utility-adjusted survival. A literature review was performed to estimate 1) the prevalence of axillary lymph node disease for early-stage breast carcinoma, 2) the sensitivity and specificity of SND and AND, 3) the 5-year overall survival as a function of axillary lymph node involvement, 4) the risk of arm lymphedema as a function of the intervention performed, and 5) the utility correction (Uc; impairment of quality of life) for arm lymphedema.

RESULTS

The NNT method of analysis favored SND over nearly the entire range of parameters with a sign change to a negative value occurring only as Uc becomes very close to unity. This suggests the superiority of the SND approach. Only when there is minimal loss of utility does AND become favored and then only minimally.

CONCLUSIONS

Compared with AND, SND improves the utility-adjusted survival in patients with early-stage breast carcinoma. This finding is quite robust and was found to remain constant over a range of values for utility and lymph node prevalence.