Assessment of residual setup errors for anatomical sub-structures in image-guided head-and-neck cancer radiotherapy.

BACKGROUND: To quantify residual setup errors (RSE) and required planning target volumes (PTV) margins in head-and-neck cancer (HNC) radiotherapy when using daily image guidance (IG) and less-than-daily IG protocols. MATERIAL AND METHODS: Daily on-line kV-image registrations of 80 HNC patients (2640 imaged treatment fractions) were retrospectively studied to analyze RSE. Less-than-daily imaging protocols, using different action levels, were simulated on the data. To quantify local RSE; single rigid bony structures were defined as landmarks. The RSEs and required PTV margins were computed for each sub-structure with and without daily IG. RESULTS: For less-than-daily IG protocols the setup accuracy was more dependent on frequent imaging throughout the treatment course than the number of initially imaged fractions. With daily IG the RSE of the sub-structures ranged from 0.6 mm to 2.3 mm (systematic) and from 1.0 mm to 1.7 mm (random). Required PTV margins for the sub-regions ranged from 4.5 mm to 9.3 mm with no IG and from 2.3 mm to 6.8 mm with daily IG. CONCLUSION: Anatomical changes over the treatment course require frequent IG to achieve accurate dose delivery using highly conformal radiotherapy techniques. The current study shows that considerable local RSE may remain even with daily IGRT. The comprehension of local RSEs in HNC radiotherapy is important when designating PTV margins as well as tolerance levels for couch correction and plan adaption.

Retrospective cohort study of bronchial doses and radiation-induced atelectasis after stereotactic body radiation therapy of lung tumors located close to the bronchial tree.

PURPOSE: To evaluate the dose-response relationship between radiation-induced atelectasis after stereotactic body radiation therapy (SBRT) and bronchial dose. METHODS AND MATERIALS: Seventy-four patients treated with SBRT for tumors close to main, lobar, or segmental bronchi were selected. The association between incidence of atelectasis and bronchial dose parameters (maximum point-dose and minimum dose to the high-dose bronchial volume [ranging from 0.1 cm(3) up to 2.0 cm(3)]) was statistically evaluated with survival analysis models. RESULTS: Prescribed doses varied between 4 and 20 Gy per fraction in 2-5 fractions. Eighteen patients (24.3%) developed atelectasis considered to be radiation-induced. Statistical analysis showed a significant correlation between the incidence of radiation-induced atelectasis and minimum dose to the high-dose bronchial volumes, of which 0.1 cm(3) (D(0.1cm3)) was used for further analysis. The median value of D(0.1cm3) (α/ß = 3 Gy) was EQD(2,LQ) = 147 Gy3 (range, 20-293 Gy3). For patients who developed atelectasis the median value was EQD(2,LQ) = 210 Gy3, and for patients who did not develop atelectasis, EQD(2,LQ) = 105 Gy3. Median time from treatment to development of atelectasis was 8.0 months (range, 1.1-30.1 months). CONCLUSION: In this retrospective study a significant dose-response relationship between the incidence of atelectasis and the dose to the high-dose volume of the bronchi is shown.

Toxicity after reirradiation of pulmonary tumours with stereotactic body radiotherapy.

PURPOSE: To assess toxicity and feasibility of reirradiation with stereotactic body radiotherapy (SBRT) after prior lung SBRT for primary lung cancer or lung metastases. PATIENTS AND MATERIALS: Twenty-nine patients reirradiated with SBRT on 32 lung lesions (11 central, 21 peripheral) were retrospectively reviewed. Median follow-up time was 12 months (range 1-97). The primary endpoint was toxicity, secondary endpoints were local control and overall survival time. Toxicity was scored according to the NCI-CTCAE version 3. RESULTS: Grade 3-4 toxicity was scored 14 times in eight patients. Three patients died because of massive bleeding (grade 5). Larger clinical target volumes (CTV) and central tumour localization were associated with more severe toxicity. There was no correlation between mean lung dose (MLD) and lung toxicity. Local control at 5 months after reirradiation was 52%, as assessed by CT-scan (n=12) or X-thorax (n=3). A larger CTV was associated with poorer local control. Kaplan-Meier estimated 1- and 2-year survival rates were 59% and 43%, respectively. CONCLUSIONS: Reirradiation with SBRT is feasible although increased risk of toxicity was reported in centrally located tumours. Further research is warranted for more accurate selection of patients suitable for reirradiation with SBRT.

Hyperthyroidism and suicide: a retrospective cohort study in Sweden.

OBJECTIVES: Mental symptoms and impaired quality of life commonly occur in patients treated for hyperthyroidism. Our aim was to determine whether a history of hyperthyroidism implies an increased risk of suicide. DESIGN: Historic cohort study of 43,633 patients treated with radioiodine or surgery for hyperthyroidism between 1950 and 2005. The majority of the radioiodine-treated patients came from Stockholm. Two comparison cohorts consisted of 44,921 patients registered with an operation for atoxic nodular goitre between 1965 and 2005, and 354,861 patients with a cholecystectomy between 1965 and 2001. METHODS: Subjects were followed from the date of diagnosis until death, emigration or end of follow-up. Information on outcome was obtained from population and health registers. RESULTS: The number of observed suicide deaths was 134 in the study cohort. A naive comparison with the age-, sex- and calendar period-matched general Swedish population yielded a moderately increased standardized mortality ratio (SMR), but stratifications revealed that the excess was mainly driven by women from Stockholm, whose baseline suicide risk was higher than for women in the rest of Sweden. Using the population rates from Stockholm, the SMR among Stockholm women with Graves' disease was 1.14 (95% confidence intervals (CI) 0.66-1.86) and toxic goitre 0.99 (95% CI 0.51-1.72). A direct comparison between the study cohort and the combined comparison cohorts, with multiple adjustments (including adjustment for residence in Stockholm), yielded a relative risk of suicide of 0.93 (0.68-1.26). CONCLUSIONS: This study did not confirm an increased risk of suicide among patients treated for hyperthyroidism.

The role of radiotherapy in treatment of stage I non-small cell lung cancer.

Most information on results with radiotherapy (RT) for stage I non-small cell lung cancer (NSCLC) is based on retrospective studies on RT-treated inoperable NSCLC cases. Thus, the role of RT for stage I NSCLC, as a curative modality, has not yet been established. A literature search for studies on stage I non-small cell lung carcinoma (NSCLC) treated by RT alone resulted in 18 papers published between 1988 and 2000. The majority of stage I patients received RT treatment because they were medically inoperable. The main contraindications for surgery were grave impairment of pulmonary function and serious cardiovascular disease. Local recurrence was the most common reason for treatment failure (median value 40%) but varied highly between the studies, ranging from 6.4 to 70%. In contrast with local recurrence, regional failure was not a major problem (0-3.2%). Generally, smaller tumour size, low T-stage and increased dose had a favourable impact on local control and increased local control was followed by increased survival. No serious treatment complications were recorded in the majority of these studies. Overall treatment results were, however, disappointing. The median survival in these studies ranged from 18 to 33 months. The 3- and 5-year overall survival was 34+/-9 and 21+/-8% (mean value+/-1 S.E.), respectively. The cause-specific survival at 3 and 5 years was 39+/-10 and 25+/-9% (mean value+/-1 S.E.), respectively. Dose escalation, in a setting with conformal RT using involved field or stereotactic RT, should be the focus of developmental therapeutic strategies with inoperable stage I NSCLC to improve local control and survival.