Doses to the right coronary artery and the left anterior descending coronary artery and death from ischemic heart disease after breast cancer radiotherapy: a case-control study in a population-based cohort

BACKGROUND AND PURPOSE

Doses to the coronary arteries in breast cancer (BC) radiotherapy (RT) have been suggested to be a risk predictor of long-term cardiac toxicity after BC treatment. We investigated the dose-risk relationships between near maximum doses (Dmax) to the right coronary artery (RCA) and left anterior descending coronary artery (LAD) and ischemic heart disease (IHD) mortality after BC RT.

PATIENTS AND METHODS

In a cohort of 2,813 women diagnosed with BC between 1958 and 1992 with a follow-up of at least 10 years, we identified 134 cases of death due to IHD 10-19 years after BC diagnosis. For each case, one control was selected within the cohort matched for age at diagnosis. 3D-volume and 3D-dose reconstructions were obtained from individual RT charts. We estimated the Dmax to the RCA and the LAD and the mean heart dose (MHD). We performed conditional logistic regression analysis comparing piecewise spline transformation and simple linear modeling for best fit.

RESULTS

There was a linear dose-risk relationship for both the Dmax to the RCA (odds ratio [OR]/Gray [Gy] 1.03 [1.01-1.05]) and the LAD (OR/Gy 1.04 [1.02-1.06]) in a multivariable model. For MHD there was a linear dose-risk relationship (1,14 OR/Gy [1.08-1.19]. For all relationships, simple linear modelling was superior to spline transformations.

INTERPRETATION

Doses to both the RCA and LAD are independent risk predictors of long-term cardiotoxicity after RT for BC In addition to the LAD, the RCA should be regarded as an organ at risk in RT planning.

Epidermal Keratinocyte Depletion during Five Weeks of Radiotherapy is Associated with DNA Double-Strand Break Foci, Cell Growth Arrest and Apoptosis: Evidence of Increasing Radioresponsiveness and Lack of Repopulation; the Number of Melanocytes Remains Unchanged

During fractionated radiotherapy, epithelial cell populations are thought to decrease initially, followed by accelerated repopulation to compensate cell loss. However, previous findings in skin with daily 1.1 Gy dose fractions indicate continued and increasing cell depletion. Here we investigated epidermal keratinocyte response with daily 2 Gy fractions as well as accelerated and hypofractionation. Epidermal interfollicular melanocytes were also assessed. Skin-punch biopsies were collected from breast cancer patients before, during and after mastectomy radiotherapy to the thoracic wall with daily 2 Gy fractions for 5 weeks. In addition, 2.4 Gy radiotherapy four times per week and 4 Gy fractions twice per week for 5 weeks, and two times 2 Gy daily for 2.5 weeks, were used. Basal keratinocyte density of the interfollicular epidermis was determined and immunostainings of keratinocytes for DNA double-strand break (DSB) foci, growth arrest, apoptosis and mitosis were quantified. In addition, interfollicular melanocytes were counted. Initially minimal keratinocyte loss was observed followed by pronounced depletion during the second half of treatment and full recovery at 2 weeks post treatment. DSB foci per cell peaked towards the end of treatment. p21-stained cell counts increased during radiotherapy, especially the second half. Apoptotic frequency was low throughout radiotherapy but increased at treatment end. Mitotic cell count was significantly suppressed throughout radiotherapy and did not recover during weekend treatment gaps, but increased more than threefold compared to unexposed skin 2 weeks post-radiotherapy. The number of melanocytes remained constant over the study period. Germinal keratinocyte loss rate increased gradually during daily 2 Gy fractions for 5 weeks, and similarly for hypofractionation. DSB foci number after 2 Gy irradiation revealed an initial radioresistance followed by increasing radiosensitivity. Growth arrest mediated by p21 strongly suggests that cells within or recruited into the cell cycle during treatment are at high risk of loss and do not contribute significantly to repopulation. It is possible that quiescent (G₀) cells at treatment completion accounted for the accelerated post-treatment repopulation. Recent knowledge of epidermal tissue regeneration and cell cycle progression during genotoxic and mitogen stress allows for a credible explanation of the current finding. Melanocytes were radioresistant regarding cell depletion.

Radiation Therapy to the Plexus Brachialis in Breast Cancer Patients: Analysis of Paresthesia in Relation to Dose and Volume

PURPOSE

To identify volume and dose predictors of paresthesia after irradiation of the brachial plexus among women treated for breast cancer.

METHODS AND MATERIALS

The women had breast surgery with axillary dissection, followed by radiation therapy with (n=192) or without irradiation (n=509) of the supraclavicular lymph nodes (SCLNs). The breast area was treated to 50 Gy in 2.0-Gy fractions, and 192 of the women also had 46 to 50 Gy to the SCLNs. We delineated the brachial plexus on 3-dimensional dose-planning computerized tomography. Three to eight years after radiation therapy the women answered a questionnaire. Irradiated volumes and doses were calculated and related to the occurrence of paresthesia in the hand.

RESULTS

After treatment with axillary dissection with radiation therapy to the SCLNs 20% of the women reported paresthesia, compared with 13% after axillary dissection without radiation therapy, resulting in a relative risk (RR) of 1.47 (95% confidence interval [CI] 1.02-2.11). Paresthesia was reported by 25% after radiation therapy to the SCLNs with a V40 Gy ≥ 13.5 cm(3), compared with 13% without radiation therapy, RR 1.83 (95% CI 1.13-2.95). Women having a maximum dose to the brachial plexus of ≥55.0 Gy had a 25% occurrence of paresthesia, with RR 1.86 (95% CI 0.68-5.07, not significant).

CONCLUSION

Our results indicate that there is a correlation between larger irradiated volumes of the brachial plexus and an increased risk of reported paresthesia among women treated for breast cancer.

A method to estimate composite doses for organs at risk in prostate cancer patients treated with EBRT in combination with HDR BT

BACKGROUND

When evaluating late toxicity after combined external beam radiation therapy (EBRT) and high-dose rate brachytherapy (HDR BT) prostate cancer treatments, it is important that the composite dose distribution is taken into account. This can be challenging if organ-at-risk (OAR) dose data are incomplete, i.e. due to a limited ultrasound imaging field-of-view in the HDR BT procedure. This work proposes a method that provides estimates of composite OAR doses for such situations.

MATERIAL AND METHODS

Original EBRT, simulated HDR BT, and composite dose-volume histograms (DVHs) for 10 pelvic OARs in 30 prostate cancer cases were used for method implementation and evaluation (EBRT: 25×2.0 Gy+BT: 2×10.0 Gy). The proposed method used information from the EBRT DVH to estimate OAR BT doses (with or without fractionation correction). Coefficients of determination (R2) were calculated for linear relationships between several EBRT DVH parameters and a BT DVH parameter of interest. The largest R2 value decided the relationship that best predicted the BT DVH parameter. The composite dose value was then calculated by adding the EBRT DVH and the estimated BT DVH parameter values and was compared to the reference composite value (in 1200 OAR/patient/parameter cases).

RESULTS

The linear relationships had an average R2 of 0.68 (range 0.42-0.88). Only one ninth of the 1200 estimated composite DVH values differed more than 2 Gy from their reference values.

CONCLUSION

Given a successful implementation, the proposed method only requires original or simulated BT plan data for a subset of patients to estimate composite doses for large study populations in a time-efficient manner. This can assist in evaluating radiation-induced late toxicity in multimodality treatments with limited OAR dose data.

Dose-response relationships for an atomized symptom of fecal incontinence after gynecological radiotherapy

PURPOSE

The aim of this study was to investigate what bowel organ and delivered dose levels are most relevant for the development of 'emptying of all stools into clothing without forewarning' so that the related dose-responses could be derived as an aid in avoiding this distressing symptom in the future.

MATERIAL AND METHODS

Of the 77 gynecological cancer survivors treated with radiotherapy (RT) for gynecological cancer, 13 developed the symptom. The survivors were treated between 1991 and 2003. The anal-sphincter region, the rectum, the sigmoid and the small intestines were all delineated and the dose-volume histograms were exported for each patient. The dose-volume parameters were estimated fitting the data to the Relative Seriality (RS), the Lyman and the generalized Equivalent Uniform Dose (gEUD) model.

RESULTS

The dose-response parameters for all three models and four organs at risk (OARs) were estimated. The data from the sigmoid fits the studied models best: D50 was 58.8 and 59.5 Gy (RS, Lyman), γ50 was 1.60 and 1.57 (RS, Lyman), s was 0.32, n was 0.13 and a was 7.7 (RS, Lyman, gEUD). The estimated volume parameters indicate that the investigated OARs behave serially for this endpoint. Our results for the three models studied indicate that they have the same predictive power (similar LL values) for the symptom as a function of the dose for all investigated OARs.

CONCLUSIONS

In our study, the anal-sphincter region and sigmoid fit our data best, but all OARs were found to have steep dose-responses for 'emptying of all stools into clothing without forewarning' and thus, the outcome can be predicted with an NTCP model. In addition, the dose to the four studied OARs may be considered when minimizing the risk of the symptom.

Urethral pain among prostate cancer survivors 1 to 14 years after radiation therapy

PURPOSE

To investigate how treatment-related and non-treatment-related factors impact urethral pain among long-term prostate cancer survivors.

METHODS AND MATERIALS

Men treated for prostate cancer with radiation therapy at the Sahlgrenska University Hospital in Göteborg, Sweden from 1993 to 2006 were approached with a study-specific postal questionnaire addressing symptoms after treatment, including urethral burning pain during urination (n=985). The men had received primary or salvage external-beam radiation therapy (EBRT) or EBRT in combination with brachytherapy (BT). Prescribed doses were commonly 70 Gy in 2.0-Gy fractions for primary and salvage EBRT and 50 Gy plus 2×10.0 Gy for EBRT+BT. Prostatic urethral doses were assessed from treatment records. We also recruited 350 non-pelvic-irradiated, population-based controls matched for age and residency to provide symptom background rates.

RESULTS

Of the treated men, 16% (137 of 863) reported urethral pain, compared with 11% (27 of 242) of the controls. The median time to follow-up was 5.2 years (range, 1.1-14.3 years). Prostatic urethral doses were similar to prescription doses for EBRT and 100% to 115% for BT. Fractionation-corrected dose and time to follow-up affected the occurrence of the symptom. For a follow-up≥3 years, 19% of men (52 of 268) within the 70-Gy EBRT+BT group reported pain, compared with 10% of men (23 of 222) treated with 70 Gy primary EBRT (prevalence ratio 1.9; 95% confidence interval 1.2-3.0). Of the men treated with salvage EBRT, 10% (20 of 197) reported urethral pain.

CONCLUSIONS

Survivors treated with EBRT+BT had a higher risk for urethral pain compared with those treated with EBRT. The symptom prevalence decreased with longer time to follow-up. We found a relationship between fractionation-corrected urethral dose and pain. Among long-term prostate cancer survivors, the occurrence of pain was not increased above the background rate for prostatic urethral doses up to 70 Gy3.

Compromised quality of life in adult patients who have received a radiation dose towards the basal part of the brain. A case-control study in long-term survivors from cancer in the head and neck region

Background

Adult patients with hypothalamic-pituitary disorders have compromised quality of life (QoL). Whether this is due to their endocrine consequences (hypopituitarism), their underlying hypothalamic-pituitary disorder or both is still under debate. The aim of this trial was to measure quality of life (QoL) in long-term cancer survivors who have received a radiation dose to the basal part of the brain and the pituitary.

Methods

Consecutive patients (n=101) treated for oropharyngeal or epipharyngeal cancer with radiotherapy followed free of cancer for a period of 4 to10 years were identified. Fifteen patients (median age 56 years) with no concomitant illness and no hypopituitarism after careful endocrine evaluation were included in a case-control study with matched healthy controls. Doses to the hypothalamic-pituitary region were calculated. QoL was assessed using the Symptom check list (SCL)-90, Nottingham Health Profile (NHP), and Psychological Well Being (PGWB) questionnaires. Level of physical activity was assessed using the Baecke questionnaire.

Results

The median accumulated dose was 1.9 Gy (1.5–2.2 Gy) to the hypothalamus and 2.4 Gy (1.8–3.3 Gy) to the pituitary gland in patients with oropharyngeal cancer and 6.0–9.3 Gy and 33.5–46.1 Gy, respectively in patients with epipharyngeal cancer (n=2). The patients showed significantly more anxiety and depressiveness, and lower vitality, than their matched controls.

Conclusion

In a group of long time survivors of head and neck cancer who hade received a low radiation dose to the hypothalamic-pituitary region and who had no endocrine consequences of disease or its treatment QoL was compromised as compared with well matched healthy controls.

The effect of air cavity size in cylindrical ionization chambers on the measurements in high-energy radiotherapy photon beams--an experimental study

The present investigation is a continuation of a previous study on the effect of the diameter of the air cavity in cylindrical ionization chambers on perturbation correction factors. Measurements were made using high-energy radiotherapy photon beams (4, 6 and 15 MV) in a water phantom. Two different pairs of cylindrical ionization chambers were used. The chambers in each pair had identical materials and construction but different air cavity diameters. The same methods were employed as in our previous investigation. The diameter of the air cavity in cylindrical ionization chambers influences the mass ionization (the measured ionization expressed per unit mass of air in the chamber air cavity) at the depth where the maximum ionization is observed and a normalization at this depth is therefore not correct. The corrections obtained at depths of 50 and 100 mm in the phantom showed that the air cavity diameter in cylindrical ionization chambers has a greater effect on the perturbation effects than the photon beam quality. The corrections found at depths of 50 and 100 mm are smaller than those currently used in dosimetry protocols.

Relative importance of hip and sacral pain among long-term gynecological cancer survivors treated with pelvic radiotherapy and their relationships to mean absorbed doses

PURPOSE

To investigate the relative importance of patient-reported hip and sacral pain after pelvic radiotherapy (RT) for gynecological cancer and its relationship to the absorbed doses in these organs.

METHODS AND MATERIALS

We used data from a population-based study that included 650 long-term gynecological cancer survivors treated with pelvic RT in the Gothenburg and Stockholm areas in Sweden with a median follow-up of 6 years (range, 2-15) and 344 population controls. Symptoms were assessed through a study-specific postal questionnaire. We also analyzed the hip and sacral dose-volume histogram data for 358 of the survivors.

RESULTS

Of the survivors, one in three reported having or having had hip pain after completing RT. Daily pain when walking was four times as common among the survivors compared to controls. Symptoms increased in frequency with a mean absorbed dose >37.5 Gy. Also, two in five survivors reported pain in the sacrum. Sacral pain also affected their walking ability and tended to increase with a mean absorbed dose >42.5 Gy.

CONCLUSIONS

Long-term survivors of gynecological cancer treated with pelvic RT experience hip and sacral pain when walking. The mean absorbed dose was significantly related to hip pain and was borderline significantly related to sacral pain. Keeping the total mean absorbed hip dose below 37.5 Gy during treatment might lower the occurrence of long-lasting pain. In relation to the controls, the survivors had a lower occurrence of pain and pain-related symptoms from the hips and sacrum compared with what has previously been reported for the pubic bone.

Experimental investigation of the effect of air cavity size in cylindrical ionization chambers on the measurements in ⁶⁰Co radiotherapy beams

In the late 1970s, Johansson et al (1978 Int. Symp. National and International Standardization of Radiation Dosimetry (Atlanta 1977) vol 2 (Vienna: IAEA) pp 243-70) reported experimentally determined displacement correction factors (p(dis)) for cylindrical ionization chamber dosimetry in ⁶⁰Co and high-energy photon beams. These p(dis) factors have been implemented and are currently in use in a number of dosimetry protocols. However, the accuracy of these factors has recently been questioned by Wang and Rogers (2009a Phys. Med. Biol. 54 1609-20), who performed Monte Carlo simulations of the experiments performed by Johansson et al. They reported that the inaccuracy of the p(dis) factors originated from the normalization procedure used by Johansson et al. In their experiments, Johansson et al normalized the measured depth-ionization curves at the depth of maximum ionization for each of the different ionization chambers. In this study, we experimentally investigated the effect of air cavity size of cylindrical ionization chambers in a PMMA phantom and ⁶⁰Co γ-beam. Two different pairs of air-filled cylindrical ionization chambers were used. The chambers in each pair had identical construction and materials but different air cavity volume (diameter). A 20 MeV electron beam was utilized to determine the ratio of the mass of air in the cavity of the two chambers in each pair. This ratio of the mass of air in each pair was then used to compare the ratios of the ionizations obtained at different depths in the PMMA phantom and ⁶⁰Co γ-beam using the two pairs of chambers. The diameter of the air cavity of cylindrical ionization chambers influences both the depth at which the maximum ionization is observed and the ionization per unit mass of air at this depth. The correction determined at depths of 50 mm and 100 mm is smaller than the correction currently used in many dosimetry protocols. The results presented here agree with the findings of Wang and Rogers' Monte Carlo simulations and show that the normalization procedure employed by Johansson et al is not correct.

Risk factors of developing long-lasting breast pain after breast cancer radiotherapy

PURPOSE

Postoperative radiotherapy decreases breast cancer mortality. However, studies have revealed a long-lasting breast pain among some women after radiotherapy. The purpose of this study was to identify risk factors that contribute to breast pain after breast cancer radiotherapy.

METHODS AND MATERIALS

We identified 1,027 recurrence-free women in two cohorts of Swedish women treated for breast cancer. The women had breast-conserving surgery and postoperative radiotherapy, the breast was treated to 48 Gy in 2.4-Gy fractions or to 50 Gy in 2.0-Gy fractions. Young women received a boost of up to 16 Gy. Women with more than three lymph node metastases had locoregional radiotherapy. Systemic treatments were given according to health-care guidelines. Three to 17 years after radiotherapy, we collected data using a study-specific questionnaire. We investigated the relation between breast pain and potential risk modifiers: age at treatment, time since treatment, chemotherapy, photon energy, fractionation size, boost, loco-regional radiotherapy, axillary surgery, overweight, and smoking.

RESULTS

Eight hundred seventy-seven women (85%) returned the questionnaires. Among women up to 39 years of age at treatment, 23.1% had breast pain, compared with 8.7% among women older than 60 years (RR 2.66; 95% CI 1.33-5.36). Higher age at treatment (RR 0.96; 95% CI 0.94-0.98, annual decrease) and longer time since treatment (RR 0.93; 95% CI 0.88-0.98, annual decrease) were related to a lower occurrence of breast pain. Chemotherapy increased the occurrence of breast pain (RR 1.72; 95% CI 1.19-2.47). In the multivariable model only age and time since treatment were statistically significantly related to the occurrence of breast pain. We found no statistically significant relation between breast pain and the other potential risk modifiers.

CONCLUSIONS

Younger women having undergone breast-conserving surgery with postoperative radiotherapy report a higher occurrence of long-lasting breast pain compared to older women. Time since treatment may decrease the occurrence of pain.

Tobacco smoking and long-lasting symptoms from the bowel and the anal-sphincter region after radiotherapy for prostate cancer

BACKGROUND AND PURPOSE

Tobacco smoking can cause vascular injury, tissue hypoxia and fibrosis as can ionizing radiation. However, we do not know if tobacco smoking increases the risk of long-term side effects after radiotherapy for prostate cancer.

METHODS

We identified 985 men treated with radiotherapy for prostate cancer between 1993 and 2006. In 2008, long-lasting symptoms appearing after radiotherapy for prostate cancer were assessed through a study-specific questionnaire as were smoking habits and demographic factors of all these men. In the questionnaire the prostate-cancer survivors were asked to report symptom occurrence the previous six months.

RESULTS

We obtained information on tobacco smoking from 836 of the 985 prostate-cancer survivors with a median time to follow-up of six years (range 2-14 years). The prevalence ratio of defecation urgency among current smokers compared to never smokers was 1.6 (95% CI 1.2-2.2). Corresponding prevalence ratio for diarrhea was 2.8 (95% CI 1.2-6.5), the sensation of bowel not completely emptied after defecation 2.1 (95% CI 1.3-3.3) and for sudden emptying of all stools into clothing without forewarning 4.7 (95% CI 2.3-9.7).

CONCLUSION

Tobacco smoking among prostate-cancer survivors treated with radiotherapy increases the risk of certain long-lasting symptoms from the bowel and anal-sphincter region.

Do we need fractionation-corrected doses in sequential two-phase treatments? A quantification of dose differences between non-corrected and corrected combined non-uniform dose distributions in normal tissue

BACKGROUND

For many tumour sites, external beam radiation therapy (EBRT) is delivered with a sequential two-phase treatment regime. Yet, there is a lack of consensus of how to add two different non-uniform dose distributions in order to evaluate the late radiation effect for normal tissue. The purpose of this novel investigation is to quantify the dose differences between non-corrected and fractionation-corrected combined non-uniform dose distributions.

MATERIAL AND METHODS

We used a model of an organ at risk (OAR) located in six different positions relative the treated volume giving 16 clinically representative two-phase treatment situations (46 Gy + 22 Gy). The linear-quadratic model was applied to correct for fractionation effects in each voxel before the doses were added. Dose differences were quantified using mean and maximum doses with corresponding fractionation-corrected doses as reference.

RESULTS

Non-corrected doses were higher than fractionation-corrected doses in all treatment situations (mean dose: p<0.001; maximum dose: p=0.003). With the OAR outside the treated volume, non-corrected doses were 3-6 Gy higher representing 10-50% of the reference dose (10-25 Gy); with the OAR included in the treated volume, 1-6 Gy higher representing 1-15% (30-60 Gy). Mean dose differences were generally larger than maximum dose differences.

CONCLUSION

Substantial dose differences were present in all of the simulated treatment situations but more apparent when the OAR was located outside the treated volume in both phases. Our findings require verification in clinical cases but nevertheless indicate a need for fractionation-corrected doses in two-phase treatments both in the daily clinical routine as well as in the modelling of late radiation effects. Our data suggest that adjusting for fractionation effects would lead to lower tolerance doses than currently suggested, in particular for OARs with parallel tissue architecture.

Symptoms 10-17 years after breast cancer radiotherapy data from the randomised SWEBCG91-RT trial

BACKGROUND

Postoperative radiotherapy decreases the risk for local recurrence and improves overall survival in women with breast cancer. We have limited information on radiotherapy-induced symptoms 10-17 years after therapy.

MATERIAL AND METHODS

Between 1991 and 1997, women with lymph node-negative breast cancer were randomised in a Swedish multi-institutional trial to breast conserving surgery with or without postoperative radiotherapy. In 2007, 10-17 years after randomisation, the group included 422 recurrence-free women. We collected data with a study-specific questionnaire on eight pre-selected symptom groups.

RESULTS

For six symptom groups (oedema in breast or arm, erysipelas, heart symptoms, lung symptoms, rib fractures, and decreased shoulder mobility) we found similar occurrence in both groups. Excess occurrence after radiotherapy was observed for pain in the breast or in the skin, reported to occur "occasionally" by 38.1% of survivors having undergone radiotherapy and surgery versus 24.0% of those with surgery alone (absolute difference 14.1%; p=0.004) and at least once a week by 10.3% of the radiotherapy group versus 1.7% (absolute difference 8.6%; p=0.001). Daily life and analgesic use did not differ between the groups.

CONCLUSIONS

Ten to 17 years after postoperative radiotherapy 1 in 12 women had weekly pain that could be attributed to radiotherapy. The symptoms did not significantly affect daily life and thus the reduced risk for local recurrence seems to outweigh the risk for long-term symptoms for most women.

End-of-life decisions as bedside rationing. An ethical analysis of life support restrictions in an Indian neonatal unit

INTRODUCTION

Hundreds of thousands of premature neonates born in low-income countries are implicitly denied treatment each year. Studies from India show that treatment is rationed even for neonates born at 32 gestational age weeks (GAW), and multiple external factors influence treatment decisions. Is withholding of life-saving treatment for children born between 28 and 32 GAW acceptable from an ethical perspective?

METHOD

A seven-step impartial ethical analysis, including outcome analysis of four accepted priority criteria: severity of disease, treatment effect, cost effectiveness and evidence for neonates born at 28 and 32 GAW.

RESULTS

The ethical analysis sketches out two possibilities: (a) It is not ethically permissible to limit treatment to neonates below 32 GAW when assigning high weight to health maximisation and overall health equality. Neonates below 32 GAW score high on severity of disease and efficiency and cost-effectiveness of treatment if one gives full weight to early years of a newborn life. It is in the child's best interest to be treated. (b) It can be considered ethically permissible if high weight is assigned to reducing inequality of welfare and maximising overall welfare and/or not granting full weight to early years of newborns is considered acceptable. From an equity-motivated health and welfare perspective, we would not accept (b), as it relies on accepting the lack of proper welfare policies for the poor and disabled in India.

CONCLUSION

Explicit priority processes in India for financing neonatal care are needed. If premature neonates are perceived as worth less than other patient groups, the reasons should be explored among a broad range of stakeholders.

Variation in position and volume of organs at risk in the small pelvis

In preparation for studies of dose volume of ionizing radiation and long-term side effects, we assessed both variation in position and volume of organs at risk in the small pelvis.

MATERIAL AND METHODS

On 10 men and seven women we delineated the sigmoid, rectum, anal sphincter, bladder, penile bulb, and cavernous bodies in two CT scans taken between five to 69 days apart.

RESULTS

The measured overlap of the two delineated volumes divided by the maximum possible overlap, was below 50% for the sigmoid in six of 17 patients, for the distal 4 cm of the sigmoid in five of 17 patients, for the rectum in none of 17 patients, for the anal sphincter in three of 17 patients and for the urinary bladder in none of 17 patients. The smaller volume divided by the larger volume was below 50% in three of 17 patients for the sigmoid, in six of 17 patients for the 4 distal cm of the sigmoid, in two of 17 patients for the rectum, in two of 17 patients for the anal sphincter and in seven of 17 patients for the urinary bladder. For the urinary bladder the largest deviation was found cranially, 4.0 cm (SD 2.0 cm), the caudal part being relatively fixed. For the rectum the largest deviation was found in the anterior wall, 1.8 cm (SD 0.7 cm), with maximum documented variation in cranial direction of 3.2 cm (SD 1.8 cm).

CONCLUSIONS

The sigmoid varies considerably in documented position with the largest deviation anteriorly, the urinary bladder change in volume with the extension mainly located cranially and for the rectum the anterior wall is the most mobile with the distension becoming more pronounced cranially. In modeling dose-volume effects one may consider our results.

Long-term treatment results for nasopharyngeal carcinoma: the Sahlgrenska University Hospital experience

Nasopharyngeal carcinoma (NPC) is a rare disease in Sweden. For evaluation of the treatment outcomes in our NPC patients, 52 new cases that were referred to our department between 1991 and 2002 were retrospectively analysed. Tumor stage, according to the 1997 AJCC staging system, was I in five, II in ten, III in 12 and IV in 25 patients. Majority of the patients (87%) had World Health Organization type II-III tumors. Neoadjuvant chemotherapy was delivered in 33 patients. Thirty-two patients received hyperfractionated accelerated radiation therapy with a median dose of 64.6Gy (1.7Gy/fr bid). Conventional external irradiation with a median dose of 66Gy (2Gy/fr) was delivered to 18 patients. An intracavitary brachy-boost of 4.5-12Gy was delivered to 40 patients. Two patients were excluded from the analysis due to treatment refusal. For the patients with tumor stages I-IVB, the 5-year disease-free and overall survival rates were 61% and 55%, respectively. The 5-year local, regional, and distant relapse-free survival rates were 70%, 92% and 77%, respectively. The most frequent late side effects were xerostomia (98%), otitis (70%) and hearing deterioration (64%). Our data suggest that optimization of the treatment outcomes in NPC patients requires implementation of new therapeutic strategies.

Accelerated radiotherapy for advanced laryngeal cancer

The purpose of this study was to evaluate a single institution's outcome for patients with advanced laryngeal cancer treated with accelerated radiotherapy (RT). Fifty-eight patients with advanced laryngeal cancer (T3/T4N0/N + M0) were treated with curative intent with accelerated RT during the period 1990-1998. Patients received radiotherapy alone or with induction chemotherapy. The 5-year local control (LC) and loco-regional control (LRC) probabilities were both 49% for T3 and 75% for T4 tumors. The 5-year disease-free survival probability was 46% and 68% and overall survival probability was 30% and 39% for T3 and T4 tumors respectively. No significant statistical difference in outcome was found, either between T3 and T4 tumors, or between patients who received induction chemotherapy and those who did not. The treatment results for advanced laryngeal cancer at this institution were comparable to those reported in the literature. The results for T3 and T4 were similar. T4 classification alone should not be an exclusion criterion for larynx preservation. Overall survival was poor, partly because of a high incidence of deaths from intercurrent diseases.

Dummy run for a phase II study of stereotactic body radiotherapy of T1-T2 N0M0 medical inoperable non-small cell lung cancer

In forthcoming multicentre studies on stereotactic body radiotherapy (SBRT) compliance with volume and dose prescriptions will be mandatory to avoid unnecessary heterogeneity bias. To evaluate compliance in a multicentre setting we used two cases from an ongoing phase II study of SBRT of T1-T2N0M0 inoperable NSCLC in a dummy run oriented on volumes and doses. Six Scandinavian centres participated. Each centre received CT-scans covering the whole lung volumes of two patients with instructions to follow the study protocol when outlining tumour and target volumes, prescribing doses and creating dose plans. Volumes and doses of the 12 dose plans were evaluated according to the study protocol. For the two patients the GTV volume range was 24 to 39 cm3 and 26 to 41 cm3, respectively. The PTV volume range was 90 to 116 cm3, and 112 to 155 cm3, respectively. For all plans the margin between CTV and PTV in all directions followed in detail the protocol. The prescribed dose was for all centres 45 Gy/3 fractions (isocentre dose about 66 Gy). The mean GTV doses ranged from 63 to 67 Gy and from 63 to 68 Gy, respectively. The minimum doses for GTV were between 50-64 Gy and between 55-65 Gy, respectively. The dose distribution was conformed to PTV for 10 of 12 plans and 2 of 12 plans from one centre had sub-optimal dose distribution. Most of the volume and dose parameters for the participating centres showed fully acceptable compliance with the study protocol.

A review of the impact of photon and proton external beam radiotherapy treatment modalities on the dose distribution in field and out-of-field; implications for the long-term morbidity of cancer survivors

The use of untraditional treatment modalities for external beam radiotherapy such as intensity modulated radiation therapy (IMRT) and proton beam therapy is increasing. This review focuses on the changes in the dose distribution and the impact on radiation related risks for long-term cancer survivors. We compare conventional radiotherapy, IMRT, and proton beam therapy based on published treatment planning studies as well as published measurements and Monte Carlo simulations of out-of-field dose distributions. Physical dose parameters describing the dose distribution in the target volume, the conformity index, the dose distribution in organs at risk, and the dose distribution in non-target tissue, respectively, are extracted from the treatment planning studies. Measured out-of-field dose distributions are presented as the dose equivalent as a function of distance from the treatment field. Data in the literature clearly shows that, compared with conventional radiotherapy, IMRT improves the dose distribution in the target volume, which may increase the probability of tumor control. IMRT also seems to increase the out-of-field dose distribution, as well as the irradiated non-target volume, although the data is not consistent, leading to a potentially increased risk of radiation induced secondary malignancies, while decreasing the dose to normal tissues close to the target volume, reducing the normal tissue complication probability. Protons show no or only minor advantage on the dose distribution in the target volume and the conformity index compared to IMRT. However, the data consistently shows that proton beam therapy substantially decreases the OAR average dose compared to the other two techniques. It is also clear that protons provide an improved dose distribution in non-target tissues compared to conventional radiotherapy and IMRT. IMRT and proton beam therapy may significantly improve tumor control for cancer patients and quality of life for long-term cancer survivors.

Swedish Cancer Society Radiation Therapy Research Investigation

In an investigation by the Swedish Cancer Society, the present status, critical issues and future aspects and prospects were described by an expert group for each of nine major areas of radiation research. A summary of the investigation is presented in this report. A more extensive summary (in Swedish) can be found at www.Cancerfonden.se. It is concluded that radiation therapy plays an increasingly important role in curative and palliative tumour treatment and presents a considerable challenge to research. Several suggestions are made that could improve the possibilities for high-quality radiation therapy research in Sweden.

Outcome in a prospective phase II trial of medically inoperable stage I non-small-cell lung cancer patients treated with stereotactic body radiotherapy

PURPOSE

The impact of stereotactic body radiotherapy (SBRT) on 3-year progression-free survival of medically inoperable patients with stage I non-small-cell lung cancer (NSCLC) was analyzed in a prospective phase II study.

PATIENTS AND METHODS

Fifty-seven patients with T1NOMO (70%) and T2N0M0 (30%) were included between August 2003 and September 2005 at seven different centers in Sweden, Norway, and Denmark and observed up to 36 months. SBRT was delivered with 15 Gy times three at the 67% isodose of the planning target volume.

RESULTS

Progression-free survival at 3 years was 52%. Overall- and cancer-specific survival at 1, 2, and 3 years was 86%, 65%, 60%, and 93%, 88%, 88%, respectively. There was no statistically significant difference in survival between patients with T1 or T2 tumors. At a median follow-up of 35 months (range, 4 to 47 months), 27 patients (47%) were deceased, seven as a result of lung cancer and 20 as a result of concurrent disease. Kaplan-Meier estimated local control at 3 years was 92%. Local relapse was observed in four patients (7%). Regional relapse was observed in three patients (5%). Nine patients (16%) developed distant metastases. The estimated risk of all failure (local, regional, or distant metastases) was increased in patients with T2 (41%) compared with those with T1 (18%) tumors (P = .027).

CONCLUSION

With a 3-year local tumor control rate higher than 90% with limited toxicity, SBRT emerges as state-of-the-art treatment for medically inoperable stage I NSCLC and may even challenge surgery in operable instances.

Radiation-induced rib fractures after hypofractionated stereotactic body radiation therapy of non-small cell lung cancer: a dose- and volume-response analysis

BACKGROUND AND PURPOSE

The aim of this study is to analyse the dose-response and the volume-response of radiation-induced rib fractures after hypofractionated stereotactic body radiation therapy (SBRT).

MATERIALS AND METHODS

During the period 1998-2005, 68 patients with medically inoperable stage I non-small cell lung cancer (NSCLC) were treated with hypofractionated SBRT to 45 Gy in 3 fractions. Among the 33 patients with complete treatment records and radiographic follow-up exceeding 15 months (median: 29 months), 13 fractures were found in seven patients. Identifying all ribs receiving at least 21 Gy, 81 ribs (13 with and 68 without fracture) in 26 patients were separately contoured and their dose-volume histograms (DVHs) were obtained. The DVHs were assessed with the mean dose and cut-off models. Maximum likelihood estimation was used to fit dose-response and volume-response curves to each model.

RESULTS

It was possible to quantify the risk of radiation-induced rib fracture using response curves and information contained in the DVHs. Absolute volumes provided better fits than relative volumes and dose-response curves were more suitable than volume-response curves. For the dose given by the 2 cm(3) cut-off volume, D(2 cm(3)), the logistic dose-response curve for three fractions was parameterised by D(50)=49.8 Gy and gamma(50)=2.05. Consequently, for a median follow-up of 29 months, if D(2 cm(3))<3 x 7.0 Gy the risk is close to 0, and the 5% and 50% risks are given by D(2 cm(3))=3 x 9.1 Gy and 3 x 16.6 Gy, respectively.

CONCLUSIONS

In this group of patients, the risk for radiation-induced rib fracture following hypofractionated SBRT was related to the dose to 2 cm(3) of the rib.