Naslov
POSITIONING Of INTRAOPERATIVE RADIOTHERAPY IN BREAST CANCER TREATMENT

Autori
Antunac, Katarina

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, stručni

Izvornik
Libri oncologici: Croatian Journal of Oncology- 15th Croatian oncology congress / Vrdoljak, Eduard ; Jazvić, Marijana - Zagreb : Klinički bolnički centar Sestre milosrdnice, 2022, 50-52

Skup
15. hrvatski onkološki kongres (HOK 2022)

Mjesto i datum
Opatija, Hrvatska, 31.03.2022. - 03.04.2022

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Domaća recenzija

Ključne riječi
breast cancer radiotherapy, intraoperative radiotherapy (IORT), external beam radiother- apy (EBRT), whole breast radiotherapy (WBRT), boost dose on tumor bed

Sažetak
Intraoperative radiotherapy (IORT) of breast cancer is not proven equivalent to external beam whole breast radiotherapy (WBRT). In the majority of cases IORT cannot replace WBRT in patients with breast cancer in whom adjuvant radiotherapy is indicated. Intraoperative radiotherapy can be delivered using electrons or photons. In ELIOT trial 1305 patients older than 48 years with early breast cancer size up to 25 mm undergoing breast conserving treatment were randomised to receive either one dose of 21 Gy delivered with 3- 10 MeV energy electrons through ELIOT system or external beam whole breast radiotherapy, prescribed dose being 50 Gy in 25 fractions followed by a boost of 10 Gy in five fractions. After a median follow up of 5.8 months, local relapse rate was 4.4% in patients who received IORT and 0.4% in patients receiving WBRT (p < 0.0001). No difference in overall survival has been observed. In TARGIT A trial patients with early breast cancer age 45 years or more were randomised to receive either IORT with TARGIT system using 50 keV photons (Intrabeam), prescribed dose being 20 Gy or WBRT, prescribed dose 45-50 Gy in 25 fraction, with or without boost dose on tumor bed. After a median follow up of 2 years and 5 months, 5-year risk for local recurrence was 3.3% for TARGIT group versus 1.3% for WBRT group (p=0.042). No difference in local relapse rate has been observed between IORT and WBRT if patients received IORT concurrently with lumpectomy (prepathology sub-group). Overall survival rates did not differ between the groups. According to some authors, evidence remains insufficient for use of IORT in women with early stage breast cancer outside of a clinical trial, due to several reasons. First of all, breast cancer local relapse rates nowadays are considerably lower than 30 years ago. At that time, women undergoing breast conserving surgery (BCS) only, had 10 year local recurrence rate of 25%, compared to 7% in case of adjuvant WBRT after BCS. In the control arm of TARGIT A trial, local recurrence rate was just 1.3%, due to progress in the overall treatment of early breast cancer. It is to expect that in patient not receiving adjuvant WBRT, local relapse rate nowadays would have been around 3%- as observed in patients undergoing IORT in TARGIT A trial. Therefore, IORT is not only inferior to WBRT, but is also probably equivalent to no irradiation at all in terms of reduction of the risk of local relapse. Also, in the meantime, robust data corroborating omission of adjuvant radiotherapy in low risk breast cancer patients has become available. NICE (The National Institute for Health and Care Excellence) guidelines clearly state that low-energy x-ray IORT (Intrabeam radiotherapy system) is not recommended for routine commissioning for adjuvant treatment of early invasive breast cancer during breast-conserving surgical removal of the tumour. NCCN does not recommend IORT as a modality to deliver partial breast irradiation, when indicated. According to ASTRO (American Society for Radiation Oncology) guidelines, electron beam IORT can be used in women with invasive cancer that otherwise can be considered “suitable” for partial breast irradiation. Nevertheless, low-energy x-ray IORT should be used just within the context of a prospective registry or clinical trial, similar to NICE guidelines. However, clinical trial data support low-energy x-ray IORT (Intrabeam) to be used to deliver boost dose on the tumor bed, when indicated. That would be in premenopausal patients, or in patients with grade 3 tumors, Her2 positive tumors, triple negative tumors or tumors with positive resection margin. All of the above, except margins, is usually known prior to breast conserving surgery and those patients can be offered IORT on tumor bed. IORT must always be followed by whole breast radiotherapy. 5 years after IORT as a tumor bed boost delivered with low kilovoltage x-rays, prescribed dose being 20 Gy and followed by whole-breast radiotherapy, low local recurrence and chronic toxicity rates were observed. At University Hospital for Tumors IORT with Intrabeam system has been in use since October 2021 as a method to deliver boost dose on tumor bed in patients with right breast cancer that would otherwise be given external beam boost dose. In conclusion, IORT with low-energy x-ray cannot replace whole breast radiotherapy but can be used to deliver boost dose on tumor bed. IORT with electrons can be used in subset of patients with low risk disease who are suitable for partial breast irradiation. It is to notice that those patients have such a low risk of tumor relapse that, most probably, do not need adjuvant radiotherapy at all.

Izvorni jezik
Engleski

Znanstvena područja
Kliničke medicinske znanosti

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