The European Institute of Oncology has recently designed and refined a new method for localisation of occult breast lesions. This method, known as R.O.L.L. (Radioguided Occult Lesion Localisation) involves the inoculation of a solution of human albumen macro-aggregates radio-labelled with radioactive technetium (99mTc) into a group of microcalcifications or a small, clinically non-palpable nodule. Under the guidance of a radioguided surgical probe, these lesions, frequently cancerous, can be targeted and surgically removed, preserving the breast’s integrity.
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Until a few years ago, no more than 5% of cases of non-invasive breast cancer were diagnosed. In the last ten years, the widespread use of instrumental analyses, especially mammography and ultrasound, has increased the identification of clinically occult tumours (i.e. not perceptible to the touch during the medical visit), which are histologically non-invasive in around 25-30% of cases. Small microcalcification clusters or opacities may in fact be the mammographic or echographic signal of an initial tumour proliferation.
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The objective of precise pre-operative localisation of the lesion and limited surgery ensuring its complete removal, with the aim of having the lesion in the centre of the removed gland tissue, was the stimulus for the development of this new technique.
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The day before the operation, the radiologist injects a small quantity of colloidal albumen labelled with a radio-isotope (Tc-99m) into the centre of an opacity (under ultrasound guidance) or into a small microcalcification cluster (under stereotactic mammographic guidance).
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Correct centring is verified by inoculating the lesion with a small quantity of a radio-opaque solution immediately after injection of the radioactive tracer.
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For further verification, the patient is sent to the nuclear medicine department, where scintigraphic breast images are taken. By overlaying the scintigraphic image, enlarged as necessary, and the mammographic image, it can be confirmed that the inoculation site corresponds exactly to the position of the lesion.
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The radioactive tracer, which is stably localised in the area of the lesion, emits signals that are detected by a radioguided surgical probe. This consists of a small metal cylinder housing a sodium iodide crystal. |
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The probe is connected to a suitably calibrated instrument that analyses the detected signal and converts it into digitally displayed pulses and an acoustic signal, whose intensity increases in direct proportion to the intensity of the detected signal. |
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In the surgeon’s hands, the probe detects the emitted radioactive signals and guides the precise localisation of the “hot spot”, which corresponds to the centre of the lesion. By moving the probe a few millimetres away from the centre towards the edge of the defined area, the signal gradually weakens and finally disappears completely. |
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In this way, the surgeon can define the limit of the surgical resection and remove a spheroidal surgical specimen with the lesion in its centre. After excision, the probe is used to ensure the complete absence of residual radioactivity in the operated area, to confirm that the entire lesion has been removed. |
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Subsequent X ray of the surgical specimen verifies its complete removal, centricity, and margins. Careful evaluation of the radioprotection parameters has demonstrated the procedure’s safety, in terms of both the low radioactivity level of the substance inoculated into the breast, which is then completely removed during surgery, and the dose absorbed by patient and surgeon. |
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R.O.L.L. is currently the method of choice at IEO for localisation of occult breast lesions, and has been used successfully in over 700 cases. The procedure enables both pathological diagnosis and surgical treatment in a single step, thus allowing fast, accurate and definitive removal of clinically occult lesions. |
