onc brain

Single-institution retrospective review of consecutive pts treated 1966-1997. 468 pts, 531 lesions; median f/u 5.8 yr (range 2-24).

Biopsy-proven epithelial skin cancer: 389 BCC, 142 SCC; 364 previously untreated, 167 recurrent. Median age 73 (BCC) and 72 (SCC).

Superficial x-rays 60%, electrons 19%, electrons + superficial 20%, megavoltage photons <2%. Volume was tumor plus microscopic extension, with an additional 1 cm margin depending on size; lead eye shields when near the eye, and bolus use evolved over time.

Local control (relapse-free from RT start), cosmesis (telangiectasia, pigment change, fibrosis) and complications.

Overall LC 89%; untreated 93% vs recurrent 80%. On multivariate analysis, fraction size (p=0.01), lesion diameter and histology (p<0.01) predicted local failure; modality did not (p=0.345).

Complications 5.8% overall (13% for lesions >5 cm), mainly soft-tissue necrosis: 9% of SCC vs 2% of BCC. Fair/poor cosmesis was 4% with superficial RT vs 12% electrons and 19% combination.

The same institution's 1986 series (Lovett et al.) found electrons worse on multivariate analysis. Here that association disappears, which the authors attribute to wider electron margins in later years. The <2 Gy/fx failure signal matches Silva et al. in pinna lesions.

Treatment spans three decades with evolving bolus and margin policy. The cosmesis data are missing for 15-25% of untreated lesions, and the SCC dose cells are small, so the absent SCC dose response may reflect low power.

The data support RT as definitive therapy for early BCC/SCC and put the main lever on fraction size and lesion size, not beam type. Recurrent SCC carries the poorest control and the most cosmetic cost, so failure at first treatment is expensive.

Retrospective single-institution series spanning three decades; modality chosen by lesion size, not randomized, so dose and modality associations are confounded. No surgical comparator.

Retrospective single-centre series, 434 tumours in 333 pts treated January 2001 to December 2006. Analysis per tumour; LRF and MFS as one minus cumulative incidence with death as competing risk.

Biopsy-proven BCC (n=332) or SCC (n=102), primary RT (n=386) or postop for residual disease (n=48). Median age 74.8y BCC, 78.3y SCC; 59.4% face, 22.4% elsewhere on head.

Electrons, 54 Gy/18 fx of 3 Gy (n=159) or 44 Gy/10 fx of 4.4 Gy (n=275), four fx per week. 4-12 MeV by tumour depth, tumour + 1 cm margin, copper foil to offset skin sparing.

No significant LRF difference between schedules in BCC (p=0.67) or SCC (p=0.46). T stage was the only factor associated with local recurrence (p=0.036); gender, age, histology, indication, site, dose and lesion number were not.

Toxicity not reported beyond cosmesis. In a 14-pt pilot, pt-scored good/fair cosmesis was 75% (54 Gy) and 100% (44 Gy), observer-scored 87% and 83%, no significant difference.

The authors cite RT local control of 87-97% for BCC and 56-91% for SCC in prior series, placing these rates at or above that range. They describe them as comparable to surgical series.

Frail pts were moved to 44 Gy before it became standard, which may bias toward fewer recurrences being seen (competing deaths) rather than toward better control. SCC CIs are wide (54 Gy lower bound 79.1%), so equivalence for SCC is not shown.

The authors argue follow-up was adequate because recurrences came early (median 10.4 mo BCC, 3.3 mo SCC). They conclude 44 Gy/10 fx is optimal for T1-T2 disease. The data support non-inferior-looking control at small size, not a formal non-inferiority claim.

Single-centre retrospective; schedule assigned by era and frailty, older 44 Gy cohort with shorter follow-up; univariate only, 15 events total. Cosmesis from 14 pts.

Single-centre analysis of a prospectively maintained database, RT delivered 2007-2011. Recurrence was assessed clinically. Univariate then backwards logistic regression, per tumour, with no correction for multiple lesions per pt.

389 pts, 448 BCC/SCC lesions, median age 78 (41-99). 67.9% <2 cm; 9% in immunosuppressed pts. Primary 53.3%, recurrent 29.7%, postoperative 16.7%.

Orthovoltage 100-300 kV, electrons 6-18 MeV with bolus, or 1-2 field photons (IMRT selectively). Most common schedules 50 Gy/20 fx and 40 Gy/10 fx. GTV by clinical mark-up plus a 1-2 cm margin; CT planning for deep tumours.

LC 84.2% at median f/u 18.4 mo; median time to recurrence 11.4 mo. Independent predictors were age, size ≥2 cm, immunosuppression and modality; EQD2 and indication (primary vs recurrent vs postop) were not.

LC sits below the ranges the authors cite (BCC 87%-98%, SCC 56%-97%). The van Hezewijk series used higher-EQD2 schedules (44/10 vs 54/18) with 3y LC 96.1% and 96.9%, but the populations are not comparable.

Logistic regression treats a time-to-event outcome as binary, so pts with 0-mo follow-up count as controlled. The 3-category modality variable cannot separate technique from tumour depth. Recurrence was not split into in-field vs marginal.

The independent risk factors are patient and tumour features, not dose, which points to selection and target coverage rather than prescription as the lever. The modality OR reflects case mix per the authors and should not drive technique choice.

Single-centre retrospective analysis; logistic model ignores censoring, modality effect confounded by indication, and 18.4-mo median f/u undercounts late BCC recurrence.

Retrospective treatment-planning comparison at one institution. 26 pts, 76 lesions, each GK plan replanned with SmartArc and HyperArc. ROC analysis on RTOG CI and NT V12Gy set the threshold volumes.

Pts treated with GK SRS for brain metastases in 2018-2019 who had two or three targets (26 selected from 121). Targets with a prescription below 12 Gy were excluded from the V12Gy analysis.

Linac plans used HD-120 MLC with FFF beams, with one or two isocenters per pt. Example prescriptions ranged from 13 Gy to 24 Gy single fraction.

The ROC thresholds were 0.4 cc for SmartArc (CI and V12Gy), 0.2 cc for HyperArc CI and 0.5 cc for HyperArc V12Gy. Averaged, they give the proposed 0.4 cc cutoff: GK is favored at or below it and VMAT above it. Median beam-on time was 56.25 min for GK vs 8.33 and 13.58 min for VMAT.

This is consistent with Liu et al, where VMAT matched or beat GK at a median volume of 0.5 cc. Potrebko et al and Vergalasova et al split targets by mean volume or diameter bins and planned more targets per pt (median eight and seven), so their cutoffs are not directly comparable.

The cutoff is an average of four ROC thresholds, not tested in a validation set. For ≤0.4 cc, Table 4 shows HyperArc CI 1.46 vs GK 1.68 (p=0.032), which conflicts with the text's 'comparable conformity'. Closely adjacent targets were dropped, and these are exactly the cases where MLC dose bridging matters most.

The useful signal is that the threshold depends on the platform: HyperArc stays competitive with GK on small-target V12Gy where SmartArc does not. No clinical endpoint links these dosimetric differences to radionecrosis or local control.

Single-institution retrospective replanning with dosimetric surrogates only. The threshold is an unvalidated average of ROC cutoffs, with no clinical toxicity or control endpoint.