A clinicopathological scoring system to select breast cancer patients for sentinel node biopsy

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Abstract

Background

Selecting patients for sentinel node biopsy, based on grade and size of the primary tumour, often results in the need for a second operation of axillary clearance since intra-operative pathological assessment of sentinel node is in its evolution at present. It may be possible to refine the clinical criteria to select patients for the type of axillary surgery.

Aim

By using a score based on clinicopathological predictors of axillary lymph node involvement, we hypothesise that it may be possible to identify patients at high or low risk of nodal involvement. This information can be used to assist patients to make informed decision regarding risks and benefits of sentinel node biopsy or axillary clearance.

Patients and methods

A score was devised based on the clinicopathological variables of 113 patients to assess the likelihood of lymph node positivity. This score was validated on an independent data set of 89 patients who underwent sentinel node biopsy and axillary surgery. Based on the score, patients were divided into two groups, high score and low score groups. For the low score group, lymph node positivity was 18% for the original score and 24% for the validation score. Lymph node positivity rate was 67% for the high score group for the original series and 65% for the validation series of patients.

Conclusion

A clinicopathological scoring system can assist in selecting patients with breast cancer for sentinel node biopsy.

Introduction

Recent studies have demonstrated that the sentinel node biopsy is a reliable and minimally invasive method for determining the status of the regional lymph nodes in patients with clinically node-negative breast cancer.1 The concept of the sentinel node being the first lymph node to contain metastatic cancer within a tumour's lymphatic basin was introduced by Cabanas following his work on carcinoma of the penis.2, 3 Morton et al. then applied this principle to malignant melanomas, and more recently this concept has gained popularity for carcinoma of the breast.4, 5

At present the selection of patients for sentinel node biopsy is commonly based on size or grade of the primary tumour. Intra-operative assessment of sentinel node is an encouraging technique but all methods of intra-operative nodal assessment are associated with false-positive and false-negative results.6, 7, 8 Imprint cytology of the sentinel nodes is simple, rapid and has good sensitivity for macrometastases. In a recent meta-analysis of sentinel node cytology in breast cancer, the pooled sensitivity for imprint cytology was 63 (95% CI, 57–69).9 This meta-analysis reported that after imprint cytology 21% of all patients having sentinel node biopsy would be correctly identified as having metastases and proceeded to complete axillary clearance at the time of sentinel node biopsy. The false-negative rate for micrometastases was 82%. On the other hand, epithelial histiocytes, germinal centre lymphocytes and activated endothelial cells can be mistaken for tumour cells, giving rise to false-positive results.10, 11 The sensitivity of the imprint cytology improves with the increasing size of the primary breast cancer. Frozen section is another method of sentinel node that has been reported to be useful in the intra-operative assessment of the sentinel node. A review of literature found that frozen section fared better than intra-operative cytology in terms of sensitivity and specificity; however, tissue loss during frozen section is an important issue when relying on frozen section for deciding completion axillary clearance.9 All breast units offering sentinel node biopsy aspire to developing a reliable method of intra-operative assessment of sentinel node but these techniques are not yet adopted widespread for routine clinical use. Axillary clearance after a positive sentinel node biopsy subjects patients to the emotional and physical traumas of a second operation and delay in the commencement of adjuvant chemotherapy.12 Alternatively, the positive nodal status of the axilla can be established by axillary ultrasound in a subgroup of patients with breast cancer, but the expertise and time resources are not widely available.

The type of axillary surgery offered to patients is generally based on the characteristics of the primary breast cancer, as well as clinical and radiological assessments of axilla. Refining the criteria for selection of patients for axillary surgery may improve the care of patients by enhancing informed consent and minimising the need for a second axillary operation.13, 14 The size of primary tumour, grade of primary tumour, age of the patient, quadrant of the breast and lymphovascular invasion are all independent predictors of lymph node involvement.15, 16 For T1a lesion node positivity rate is 15% compared to 67% in T2 lesions over 3 cm in size.14 Other studies report that for T2 lesions the incidence of lymph node positivity is 41%, which increases to 75% in T3 lesions.17 Grade I breast cancer is likely to have positive nodes in 10% of patients, while 39% of patients with grade III tumours are likely to have positive nodes.14 Other factors associated with lymph node positivity are quadrant of the breast in which the tumour is situated and whether it is palpable. Thirty-three percent of tumours situated in the upper outer quadrant of breast are node positive compared with 21% for upper inner quadrant tumours.14 Axillary nodal metastasis occurs less frequently in impalpable tumours. This may be due to the fact that the deep tumours are more likely to be impalpable and drain to the lymphatics on the surface of the pectoral fascia leading to internal mammary nodes.18 Breast cancers showing lymphovascular invasion on microscopy have a 57% chance of being node positive compared with 23% for tumours without lymphovascular invasion. Younger age is associated with increased incidence of axillary nodal metastases. In women under 35 years of age or younger, even in T1 lesions 28% of patients have nodal metastases and overall node positivity in women under 35 years of age is 59%.19 For T1a tumour node positivity rate in women under 50 years of age is 43% compared with 4% in women between 51 and 70 years of age. Women under 50 years of age carry a 40% risk of developing node positive breast cancer compared with 31% in women 51–70 years of age.20 Breast cancer patients over 70 years of age have a 23% risk of node positivity.14 Similar data have been shown in other large-scale studies.13, 21

A score based on these clinicopathological variables may reliably predict patients with likelihood of (sentinel and non-sentinel) lymph node positivity. This information can be used to assist patients to make informed decision regarding the relative benefits of sentinel node biopsy or axillary clearance thus minimising the need for a second operation and avoiding delay for oncological treatment.

Section snippets

Patients and methods

Based on the clinicopathological variables of 113 consecutive patients who underwent axillary surgery for breast cancer, a scoring system was devised to assess the likelihood of metastatic cancer in the axillary lymph nodes. These variables were age, size and grade of the primary tumour, presence of lymphovascular invasion and the quadrant of the breast (Table 1). The score was devised based on the logistic regression analysis of the clinical data. For each of these clinicopathological

High versus low score

The lowest possible score was 5 and the highest possible score was 17. For instance, a 65-year-old woman with screen detected 8 mm, impalpable grade I breast cancer situated in the lower inner quadrant of the breast and which shows no evidence of lymphovascular invasion will have a score of 6. Whereas, a 36-year-old woman with a palpable breast cancer of 42 mm, which is grade III and situated in the upper outer quadrant of breast will have a score of 17. It was found that a high score was marker

Discussion

Numerous studies on sentinel node biopsy including ALMANAC have paved the way to establish sentinel node biopsy as a minimally invasive tool in the management of axilla of women with breast cancer.22, 23 Because of a significantly lower morbidity, a high level of public acceptance has been achieved for sentinel node biopsy.24 It is suggested that eventually sentinel node biopsy may completely replace axillary clearance as the initial treatment for early breast cancer.24, 25 However, the use of

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      Patients have traditionally been selected for SLNB based on imaging size or core biopsy grade of the primary breast tumour. Clinico-pathological scoring systems incorporating patient demographics and tumour-specific parameters to improve the prediction of node positivity have been described.9,10 However, scoring calculations involving multiple parameters can prove cumbersome in the setting of busy MDT meetings.

    • A prospective study of use of a clinicopathological score to select patients for the type of axillary surgery

      2007, European Journal of Surgical Oncology
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      Whereas, a 36-year-old woman with a palpable breast cancer of 25 mm, which is grade III, shows lymphovascular invasion and situated in the upper outer quadrant of breast will have a score of 16. It was confirmed that the high score was marker of high degree of lymph node positivity and the number of patients with positive nodes increased with increasing clinicopathological score as shown in frequency distribution curves.10 The node positivity rate in the low score group was 10%.

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      2020, Current Oncology

    • Development of nomograms to predict axillary lymph node status in breast cancer patients

      2017, BMC Cancer

    • Prediction of axillary lymph node metastasis in primary breast cancer patients using a decision tree-based model

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