POSNOC - POsitive Sentinel NOde: adjuvant therapy alone versus adjuvant therapy plus Clearance or axillary radiotherapy.

A randomised controlled trial of axillary treatment in women with early stage breast cancer who have metastases in one or two sentinel nodes.

There is robust evidence that in early breast cancer, sentinel node biopsy (SNB) accurately stages the axilla with low axillary recurrence rates, comparable survival and reduced morbidity when compared with axillary node clearance (ANC). SNB has reduced risk of lymphoedema, shoulder discomfort, sensory deficits, and infections than ANC. Quality of life is superior for patients who undergo SNB.

The current UK National Institute of Clinical Excellence (NICE) guidelines recommend ANC or axillary radiotherapy (ART) for women with early stage breast cancer and one or two sentinel node metastases. ANC is usually a second operation, but some hospitals use intra-operative sentinel node assessment and so perform ANC at the same time as breast conserving surgery or mastectomy.

Axillary treatment damages lymphatic drainage from the arm, and women may subsequently develop lymphoedema. These adverse effects interfere with daily activities, are distressing, impair quality of life and are costly to the health system in terms of rehabilitative treatments (such as physiotherapy and lymphoedema clinics), as they are often irreversible and symptom relief is difficult.

All women with 1 or 2 sentinel node metastases will receive systemic therapy (chemotherapy and/or endocrine therapy). Radiotherapy to the breast is required after breast-conserving surgery and may be given after mastectomy. The aim of axillary treatment (ANC or ART) is to reduce the risk of axillary recurrence.

Axillary treatment may now be "over treatment" for early breast cancer; as diagnosis tends to be earlier so patients present with smaller tumours and a low axillary tumour burden; adjuvant therapy has improved and is better at preventing breast and axillary recurrence; and SNB has already removed the lymph nodes most likely to have metastasis.

Biological factors may be more important for recurrence than surgical removal or radiation eradication of axillary nodes. If axillary surgery is merely a staging or diagnostic procedure, then adverse effects are likely to be minimal if it is omitted and SNB alone is used to guide subsequent treatment in women with early stage breast cancer who have 1 or 2 sentinel node metastases. Also, axillary treatment (ANC or ART) was introduced several decades ago without formal evaluation and is associated with significant short and long term morbidity. Since axillary treatment was introduced, chemotherapy and hormone therapy have dramatically improved breast cancer outcomes. Therefore, it is timely to assess whether adjuvant therapy alone is an acceptable alternative to adjuvant therapy plus axillary treatment.

This UK based international clinical trial will be coordinated in Australia and NZ by Breast Cancer Trials. This trial has recruited patients in New Zealand at Waikato, Palmerston North and Rotorua hospitals. The trial is still active, but not currently recruiting. Please see this link for more information.

15 May 2023