Watch-and-wait strategy in rectal cancer: Is there a tumour size limit? Results from two pooled prospective studies.

BACKGROUND: Frequency and predictive factors for a clinical complete response (cCR) in unselected patients are unclear. MATERIAL AND METHODS: Two prospective observational studies were designed and pooled to explore predictive factors for cCR. Both studies evaluated the watch-and-wait strategy in consecutive patients; the first single-institutional study in elderly with a small tumour, the second multi-institutional study in all the patients receiving standard of care preoperative radiotherapy. RESULTS: Four hundred and ninety patients were analysed. Short-course radiotherapy alone, or with consolidation chemotherapy or chemoradiation was given to 40.6%, 40.2% and 19.2% of the patients, respectively. The median interval from the radiation start to the first tumour response assessment was 10.2 weeks for short-course radiation and 13.2 weeks for chemoradiation. Seventy-three patients had cCR and 71 underwent w&w with the median follow-up of 24 months. The regrowth rate was 26.8%. cCR rate was 39.0% for low-risk cancer (cT1-2N0), 16.8% for intermediate-risk (cT3 with unthreatened mesorectal fascia [MRF-] or cT2N+) and 5.4% for high-risk (cT4 or MRF+). In the multivariable analysis, tumour volume (or tumour length and circumferential extent) and cN status were significant predictors for cCR. In circular cancers or with a length ≥7 cm (n = 184), cCR rate was only 2.7%, sustained cCR 1.6% and the sensitivity of cCR diagnosis 23.1%. None of 27 patients with a tumour larger than 120 cm3 achieved cCR. CONCLUSIONS: Considering watch-and-wait strategy is questionable in patients with circular tumours or with tumour length ≥7 cm.

15O-H2O PET/CT as a tool for the quantitative assessment of early post-radiotherapy changes of heart perfusion in breast carcinoma patients.

OBJECTIVE: Studies examining radiation-induced heart toxicity in breast cancer patients are inconclusive. The aim of this study was to prospectively and quantitatively asses myocardial blood flow (MBF) with, for the first time, 15O-H2O PET/CT as a marker of heart damage in irradiated breast cancer patients. METHODS: 15 breast cancer patients receiving intact breast or chest wall irradiation were included in the analysis (six with right-sided and nine with left-sided breast cancer). They underwent 15O-H2O PET/CT before radiotherapy (RT) and 2 and 8 months after RT. MBF was quantitatively assessed at rest and under stress conditions in 17 heart segments distinguished according to the American Ultrasound Association classification. Regional MBF values were derived in each of the coronary artery territories. RESULTS: MBF decreased in 53% and increased in 33% of cases 2 months after RT in both left-sided and right-sided breast cancer patients. Stress testing was more sensitive than at-rest testing, demonstrating decreased perfusion in the segments supplied by the left anterior descending coronary artery (LAD) [5.41 ± 1.74 vs 4.52 ± 1.82 ml (g*min)-1; p = 0.018], which persisted at 6 months [5.41 ± 1.74 vs 4.40 ± 1.38 ml (g*min)-1; p = 0.032] and a decrease in global heart perfusion [5.14 ± 1.49 vs 4.46 ± 1.73 ml (g*min)-1; p = 0.036]. A minimal radiation dose applied to the LAD correlated with MBF changes observed 2 months after RT (r = -0.57; p = 0.032). Radiological findings were not correlated with clinical symptoms of heart toxicity. CONCLUSION: 15O-H2O PET/CT is safe and effective for the early detection and quantitative analysis of subclinical post-RT changes in heart perfusion in breast cancer patients. The LV segments supplied by the LAD are the main site of MBF changes. A minimum radiation dose deposited in the LAD may be a predictor of radiation-induced heart toxicity. Advances in knowledge: This is the first time that 15O-H2O PET/CT has been used to assess MBF after RT and the first granular description of the distribution of blood flow changes after breast cancer RT.

Radiotherapy in the prevention of heterotopic ossification after arthroplasty.

Heterotopic ossification (HO) is defined as the formation of mature lamellar bone in nonosseous tissues. HO is a common problem following total hip replacement (THR) and surgical repair of traumatic acetabular fracture (TAF). Without receiving any kind of prophylaxis the incidence of HO in patients with THR is about 30-80%. The etiology of this disorder is not well understood. The treatment of symptomatic HO is excision of heterotopic bone. Radiation therapy is a safe and effective metod for prevention of HO. The present article extensively reviews the clinical studies to define the role of radiotherapy for prevention of HO.