Abstract P2-09-17: Evaluation of the oncomine comprehensive assay for the identification of actionable mutations for therapeutic stratification from the TEAM pathology cohort

Large-scale sequencing initiatives have revealed a wealth of common and novel variants as well as copy-number aberrations, across different malignancies. This growing list of variants/aberrations can sometimes be matched to specific therapeutics. Such “actionable mutations/changes” hold promise for personalized treatment in the future, with treatments tailored to molecular abnormalities. Presently, women with hormone positive early breast cancer continue to experience improved survival on adjuvant anti-hormone therapy, but a significant number of women continue to progress. Therefore, there is a need to identify those women for whom current therapies are insufficient and to identify alternative therapeutic interventions. We explored the used of genetic profiling using a comprehensive solid tumor next generation sequencing (NGS) assay (the Oncomine Comprehensive Assay, OCA) to characterize early invasive breast cancer. The OCA is based on the Ion Torrent™ NGS platform and Ion AmpliSeq™ library preparation technology, coupled to the Oncomine™ Knowledgebase, for target selection, variant calling, and data annotations. The OCA includes 87 genes for hotspot mutation detection, 48 genes for full length sequencing and 43 genes for focal copy number assessment. The OCA provides a standardized informatics workflow and quality control (QC) parameters to process samples in a translational clinical research setting. To explore the application of the OCA to early invasive breast cancers, we performed a retrospective pilot study in a subset of cases from the TEAM trial. From the TEAM pathology samples, 420 were chosen in a case-control fashion, 413 samples were analyzed, 388 samples passed standard QC metrics, and 254 samples (65%) were found to contain 368 variants with Oncomine Knowledgebase annotations. Briefly, variants of PIK3CA were most frequent at 42.7% (157/368), followed by TP53 at 27.2% (100/368), PTEN at 5.7% (21/368), BRCA2 at 3.8% (14/368), SF3B1 (12/368), AKT1 (11/368) and PTCH1 (11/368) at 3.3%, 3.0%, 3.0%; respectively. Other variants were detected in ATM, ERBB2, RB1, FGFR2, NF1, CDKN2A, PIK3R1 and others. Amongst the 43 genes assessed for copy-number, 23 showed copy-number changes across 132 samples totalling 167 CNVs. 256 samples showed no copy-number alterations in any of the genes on the panel. ERBB2 was most frequently altered at 28.1% (47/167), followed by FGFR1 at 23.4% (39/167), CCND1 at 15.0% (25/167) and MDM2 at 10.2% (17/167). Copy-number losses were identified in TP53, RB1, PTEN, BRCA2 at 0.6% each; as well as CDKN2A at 1.8% (3/167). Analytical validation of a subset of gene variants and copy-number changes will be presented in addition to the evidence of potential future application of the Oncomine Comprehensive Assay to precision oncology goals.

Citation Format: Bayani J, Crozier C, Quintayo MA, Amemiya Y, Zhang X, Larivière M, Sadis S, Smith JM, Hasenburg A, Kieback D, Markopoulos C, Dirix L, Yaffe M, Seth A, Feilotter H, Rea D, Bartlett JMS. Evaluation of the oncomine comprehensive assay for the identification of actionable mutations for therapeutic stratification from the TEAM pathology cohort [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-09-17.

Abstract P6-09-30: Factors influencing survival among patients with HER2-positive metastatic breast cancer treated with Trastuzumab

Background: We have limited capability to predict survival among patients treated for metastatic HER2+ breast cancer. Individual patient survival varies and further research is warranted to identify significant prognostic and predictive factors influencing overall survival (OS).

Methods: We identified HER2+ metastatic breast cancer patients receiving trastuzumab (T) at the Sunnybrook Odette Cancer Centre (SOCC) from 1999-2013 through a Cancer Care Ontario Registry (n=256) and selected patients with pathology also available at SOCC (n=154). A retrospective chart review was completed documenting clinical, pathologic, laboratory and survival outcomes. OS was defined as date of 1st T therapy to death. The Kaplan-Meier method was used to estimate time-to-event outcomes. Cox proportional hazards regression models and log-rank tests were used to identify prognostic factors for overall survival (OS). Logarithmic transformations were performed for statistical purposes. Multivariable models were constructed including known prognostic factors: 1) number of visceral metastatic sites and 2) CNS metastasis. After adjusting for these two factors, stepwise selection was used to create an optimal model for additional factors. Analyses were two-sided and statistical significance was defined at the p=0.05 level.

Results: Cohort characteristics: mean age was 55 (SD: 13 years), ≥2 sites of visceral metastasis: 45%, CNS metastasis: 7%, ER positive: 53%. Median OS for the cohort was 24 months (95% CI: 21-33). Clinical factors recorded at metastatic presentation such as the presence of a visceral metastasis, having multiple sites of visceral metastasis and CNS metastasis were prognostic for overall survival in univariate models (p<0.05). ER/PR status was not of significance (p>0.05). Laboratory measures such as the neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR) and alkaline phosphatase (ALP) were of significance in univariate models (p=<0.05). The multivariable model identified older age (HR=1.18 / decade, 95% CI=1.02-1.37, p=0.030), higher PLR (HR=1.75 / log-unit, 95% CI=1.25-2.46, p=0.001), increased ALP (HR=1.87 / log-unit, 95% CI=1.41-2.49, p<0.001) and ER positivity (HR=0.63, 95% CI=0.42-0.96, p=0.032), as significant prognostic factors in addition to the presence of CNS metastasis (HR=3.19, 95% CI=1.59-6.38, p=0.001) and two or more metastatic sites (HR=2.10, 95% CI=1.19-3.70, p=0.010).

Conclusion: Our results have identified a number of prognostic factors influencing survival among patient with HER2+ breast cancer treated with T. Age, ALP, PLR and ER status were identified as significant prognostic factors after adjusting for presence of CNS metastasis and number of metastatic sites. Further study of PLR as a prognostic and predictive factor is warranted.

Citation Format: Blanchette PS, Desautels DN, Pond G, Bartlett JMS, Nofech-Mozes S, Yaffe M, Pritchard KI. Factors influencing survival among patients with HER2-positive metastatic breast cancer treated with Trastuzumab [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-09-30.

Abstract P1-05-27: Evaluation of the Oncomine focus and comprehensive assays for therapeutic stratification in early hormone receptor positive breast cancers

Large-scale sequencing initiatives have revealed a wealth of common and novel variants as well as copy-number aberrations, across different solid tumours and hematological malignancies. The growing list of variants/aberrations can sometimes be matched to specific therapeutics. Such “actionable mutations/changes” hold promise for personalized treatment, as treatments could be tailored to molecular abnormalities, rather than disease site. In breast cancer, women with hormone positive early breast cancer continue to experience improved survival on adjuvant anti-hormone therapy, but even today, a significant number of women continue to progress. Therefore there is not only a need to identify those women for whom current therapies are insufficient, but to identify alternative therapeutic interventions. The ThermoFisher Scientific Oncomine™ Focus and Oncomine™ Comprehensive Assays (OFA and OCA) are based on the Ion Torrent™ next-generation sequencing platform and Ion AmpliSeq™ library preparation technology, coupled to the Oncomine™ Knowledgebase, for target selection, variant calling, and data annotations. Both panels interrogate the most referenced oncology biomarker variants that are matched to curated published evidence from clinical trials supporting the matching of driver genetic variants with relevant potential clinical therapeutic options. The ability to identify SNVs, CNVs and fusion events in a single assay provides an unprecedented approach to maximizing the molecular information to be derived from a single tumour sample. To explore the value of the Oncomine™ assays in early invasive breast cancers, we have performed a pilot study to assess the reproducibility and accuracy of the OFA and OCA from nucleic acids extracted from formalin-fixed paraffin embedded tissues. In addition to the sequencing and copy-number data generated by these assays, we will compare these results to copy-number information generated using the Oncoscan® (Affymetrix)copy-number assay as well as information derived by Multiplex Ligation-dependent Probe Amplification-based panels (MRC-Holland) and Fluorescent in situ Hybridization (FISH). Our preliminary analyses of 35 invasive breast cancers by Oncoscan® identified the frequent whole chromosomal gains of 2, 3, 5, 7, 18, 19 and 20; gains of 1q, 7p, 8q, 11p, 16p, 17q; losses at 1p, 8p, 11q, 13, 16q, 17p and chromosome 18. High level amplifications were also identified for breast cancer related genes such as ERBB2, CCND1, MYC, FGFR1; in addition to the frequent losses of TP53, RB1, CDKN2A. Copy-number changes were confirmed by locus-specific FISH and MLPA. Data generated from the OFA and OCA from these same samples will be compared to the other platform findings and provide a snapshot of the mutational landscape of early breast cancers across these pan-cancer panels. Having established the robustness and accuracy of the assays, the applicability of the OCA in the context of improved stratification for breast cancers for prognostic and predictive tests will be discussed.

Citation Format: Bayani J, Crozier C, Zhang NX, Amemiya Y, Quintayo MA, Yan FJ, Dion D, Mccormack S, Yaffe M, Seth A, Feilotter H, Bartlett JMS. Evaluation of the Oncomine focus and comprehensive assays for therapeutic stratification in early hormone receptor positive breast cancers [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-05-27.

Three-dimensional ultrasound-based spectroscopic imaging for detection of prostate cancer in men

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Background: The objective of this translational research was to investigate the use of real-time novel three-dimension, quantitative ultrasound-based spectroscopic imaging of the prostate as a means of cancer detection.

Methods: Ten patients with T2-3 prostate cancer underwent a 6-9 MHz trans-rectal ultrasound scan of the prostate prior to radical prostatectomy. Equally spaced axial ultrasound images (0.5 cm separation) corresponding elasticity and spectroscopy data were collected in each patient. Colour-coded spectroscopic parametric maps of 0-Mhz intercept (0-Mhz), mid-band fit (MBF) and slope of line of best fit (slope) were generated indicating where the disease in the prostate gland is hypothetically located. Quantitative data (% volume of cancer over the prostate gland) were compared to whole-mount radical prostatectomy histopathology maps to determine the sensitivity and accuracy in parametrically delineating prostate cancer.

Results: Representative data indicate spectral changes were associated with the presence of co-incident disease as located on correlative histopathology whole mount sections. Of the 10 patients enrolled, 7 have been analyzed and presented here. The mean % difference between 0-MHz and MBF, with H&E, was 14% (SD 38%) and 21% (SD 24%), respectively. Gross areas of disease were readily visualized in ultrasound parametric maps and corresponded to a maximum 10dB decrease in 0-MHz or MBF. Parametric maps generated from the spectral slope offered no discrimination of disease.

Conclusions: Initial results suggest that there is good correlation between spectroscopic maps with disease on whole-mount specimens. This method may ultimately permit ultrasound-guided targeted biopsies to improve detection rates and non-invasive assessment of disease for radiotherapy planning.

No significant financial relationships to disclose.

Functional imaging of neoadjuvant chemotherapy response in women with locally advanced breast cancer using diffuse optical spectroscopy

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Background: Functional imaging with tomographic near infrared diffuse optical spectroscopy (DOS) can quantitatively measure tissue parameters such as the concentration of deoxy-hemoglobin (Hb), oxy-hemoglobin (HbO2), percent water (%water), and scattering power (SP). The purpose of this study was to evaluate the correlation between DOS functional parameters with pathologic outcomes. Methods: Patients with locally advanced breast cancer undergoing neoadjuvant chemotherapy or chemoradiotherapy were recruited to this study (n=10). Five scans were conducted per patient: a baseline scan taken up to 3 days prior to treatment and at 1 week, 4 weeks, 8 weeks, and after neoadjuvant treatment prior to surgery. Pulsed near-infrared laser light was used to scan the suspended breast at four different wavelengths and data was used for tomographic reconstruction. Volume-of-interest (VOI) weighted tissue Hb, HbO2, %water, and SP corresponding to the tumour was calculated and compared to pathological response as determined from full mount mastectomy specimens. Results: For all 10 patients the tumour-based VOI was significantly different than background tissue for all functional parameters (p<0.001). Five patients had a good pathologic response. Four patients were considered non-responders. One patient initially had a poor clinical response to chemotherapy but after a change in chemotherapy had a good clinical response. Responders and non-responders were significantly different for all of the functional parameters (p<0.05) at the 4 week scan. In the 5 patients with a good response the mean drop in Hb, HbO2, %water, and SP from baseline to the 4 week scan was 70.4% (SD=18.6), 66.5% (SD=24.5), 59.6% (SD=30.9), and 60.7% (SD=29.2), respectively. In contrast, the 4 non- responders had a mean drop of 17.7% (SD=9.8), 18.0% (SD=20.8), 15.4% (SD=11.7), and 12.6% (SD=10.2), for Hb, HbO2, %water and SP, respectively. Conclusions: Functional imaging using tomographic DOS parameters of Hb, HbO2, %water and SP could be used as an early detector of final pathologic tumour response. This could be evaluated in the future to assess response and potentially adjust chemotherapy regimens.

No significant financial relationships to disclose.

Developing a methodology for three-dimensional correlation of PET-CT images and whole-mount histopathology in non-small-cell lung cancer

BACKGROUND

Understanding the three-dimensional (3D) volumetric relationship between imaging and functional or histopathologic heterogeneity of tumours is a key concept in the development of image-guided radiotherapy. Our aim was to develop a methodologic framework to enable the reconstruction of resected lung specimens containing non-small-cell lung cancer (NSCLC), to register the result in 3D with diagnostic imaging, and to import the reconstruction into a radiation treatment planning system.

METHODS AND RESULTS

We recruited 12 patients for an investigation of radiology-pathology correlation (RPC) in nsclc. Before resection, imaging by positron emission tomography (PET) or computed tomography (CT) was obtained. Resected specimens were formalin-fixed for 1-24 hours before sectioning at 3-mm to 10-mm intervals. To try to retain the original shape, we embedded the specimens in agar before sectioning. Consecutive sections were laid out for photography and manually adjusted to maintain shape. Following embedding, the tissue blocks underwent whole-mount sectioning (4-mum sections) and staining with hematoxylin and eosin. Large histopathology slides were used to whole-mount entire sections for digitization. The correct sequence was maintained to assist in subsequent reconstruction. Using Photoshop (Adobe Systems Incorporated, San Jose, CA, U.S.A.), contours were placed on the photographic images to represent the external borders of the section and the extent of macroscopic disease. Sections were stacked in sequence and manually oriented in Photoshop. The macroscopic tumour contours were then transferred to MATLAB (The Mathworks, Natick, MA, U.S.A.) and stacked, producing 3D surface renderings of the resected specimen and embedded gross tumour. To evaluate the microscopic extent of disease, customized "tile-based" and commercial confocal panoramic laser scanning (TISSUEscope: Biomedical Photometrics, Waterloo, ON) systems were used to generate digital images of whole-mount histopathology sections. Using the digital whole-mount images and imaging software, we contoured the gross and microscopic extent of disease. Two methods of registering pathology and imaging were used. First, selected pet and ct images were transferred into Photoshop, where they were contoured, stacked, and reconstructed. After importing the pathology and the imaging contours to MATLAB, the contours were reconstructed, manually rotated, and rigidly registered. In the second method, MATLAB tumour renderings were exported to a software platform for manual registration with the original pet and ct images in multiple planes. Data from this software platform were then exported to the Pinnacle radiation treatment planning system in DICOM (Digital Imaging and Communications in Medicine) format.

CONCLUSIONS

There is no one definitive method for 3D volumetric RPC in nsclc. An innovative approach to the 3D reconstruction of resected nsclc specimens incorporates agar embedding of the specimen and whole-mount digital histopathology. The reconstructions can be rigidly and manually registered to imaging modalities such as ct and pet and exported to a radiation treatment planning system.

Is mammography adequate for screening BRCA mutation carriers with low breast density?

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Background: Several large observational studies have demonstrated that magnetic resonance imaging (MRI) is much more sensitive than M (sensitivity 71–96% vs. 28–43%) for screening women > age 25 at high risk for hereditary breast cancer. However, MRI is much more costly and less specific than M. The extent to which the low sensitivity of M in these studies is due to the greater average breast density of younger women is unknown. Accordingly, we sought to determine the sensitivity of M and MRI according to breast density for the detection of breast cancer in a screening study of BRCA mutation carriers. Methods: Breast density was measured on the screening mammogram of the contralateral breast for all women who developed in-situ or invasive breast cancer on study. Density was measured in 2 ways: qualitatively according to the four categories characterized by the BIRADS system: 1) mostly fatty, 2) scattered fibroglandular tissue, 3) heterogeneously dense, 4) extremely dense; and semi-quantitatively using computer-aided techniques with subsequent classification as: A) ≤10%, B) 11–25%, C) 26%-50%, or D) >50% density. Results: Between 11/97 and 06/05 a total of 39 cases (12 in-situ and 27 invasive) were found in 36 mutation carriers (19 BRCA1 and 17 BRCA2). Mean age of the women with cancer was 48 (range 34 to 64). Average semi-quantitative breast density for BRCA1 mutation carriers was 28% and for BRCA2 was 27%. Sensitivity of M vs. MRI for in-situ cases was 25% vs. 83%, and for invasive cases was 30% vs. 93%. Sensitivities for BRCA1 and BRCA2 mutation carriers were similar. For BIRADS 1 to 4 respectively M detected 1/3 (33%), 5/11 (45%), 4/22 (18%), and 1/3 (33%) of cases; and for density groups A to D respectively detected 2/6 (33%), 7/15 (47%), 1/11 (9%) and, 1/7 (14%). Conclusion: Although there was a trend towards decreasing mammographic sensitivity with increasing density, even among BRCA mutation carriers with low breast density mammography is an inadequate screening tool.

No significant financial relationships to disclose.

The detection of change in mammographic density

Mammographic density is associated with risk of breast cancer, and factors that change density may also change risk. There has, however, been little research into how change in serial mammograms is best detected. The purpose of the work described here was to examine the effects of different reading conditions on the detection of change in mammographic features. Mammograms were selected from women who had participated in a randomized controlled trial of screening for breast cancer. We selected two age-matched groups of subjects, one had undergone menopause after entry (n = 202) and another who had not (n = 202). Serial mammograms from these subjects were then measured four times using a computer-assisted method under different conditions: (a) films were randomized; (b) subjects were randomized (i.e., pairs of films from individuals were read one after the other), but the order of films was random and unknown to the reader; (c) subjects were randomized, and the order of films was sequential and known to the reader; and (d) subjects were randomized, and the order of films was random and unknown to the reader, but both films in each pair were read simultaneously on separate computer screens. The mean effect of the menopause on change in the mammographic measures of total, dense and nondense areas, percent density, and the associated variances were then compared. With one exception, all of the randomization and viewing methods confirmed a change in all mammographic measures at menopause and produced very similar overall results, suggesting that mammographic density is a robust measure. Compared with randomization of all films, the method in which subjects were randomized and paired films read one after the other in random and unknown order was associated with a slightly smaller mean difference and achieved a substantial reduction in variability, suggesting that it is the most sensitive method of randomization and viewing for the detection of change.

The association of breast mitogens with mammographic densities

Radiologically dense breast tissue (mammographic density) is strongly associated with risk of breast cancer, but the biological basis for this association is unknown. In this study we have examined the association of circulating levels of hormones and growth factors with mammographic density. A total of 382 subjects, 193 premenopausal and 189 postmenopausal, without previous breast cancer or current hormone use, were selected in each of five categories of breast density from mammography units. Risk factor information, anthropometric measures, and blood samples were obtained, and oestradiol, progesterone, sex hormone binding globulin, growth hormone, insulin-like growth factor-I and its principal binding protein, and prolactin measured. Mammograms were digitised and measured using a computer-assisted method. After adjustment for other risk factors, we found in premenopausal women that serum insulin-like growth factor-I levels, and in postmenopausal women, serum levels of prolactin, were both significantly and positively associated with per cent density. Total oestradiol and progesterone levels were unrelated to per cent density in both groups. In postmenopausal women, free oestradiol (negatively), and sex hormone binding globulin (positively), were significantly related to per cent density. These data show an association between blood levels of breast mitogens and mammographic density, and suggest a biological basis for the associated risk of breast cancer.

Gestational breast cancer

OBJECTIVE

To study the problems of breast imaging in gestational breast cancer.

PATIENTS AND METHOD

Retrospective review of the charts of 19 patients with breast cancer detected during pregnancy or lactation or within 1 year of delivery, who were referred to a tertiary centre for adjuvant therapy between 1986 and 1996. For 10 patients who underwent breast imaging, mammograms and breast ultrasonograms or reports were requested from outside facilities.

RESULTS

The patients ranged in age from 23 to 41 years (mean 31 years). All 19 patients presented with palpable tumours; in 7 patients, the tumours were stage T2 or higher; in 11 patients, the tumours were at an advanced stage with positive axillary nodes. In 11 of the patients there was a delay in diagnosis, which ranged from 2 to 16 months. Of the 8 mammograms that could be reviewed, 5 showed infiltrating ductal carcinomas with typical features, which were detected as a mass (in 1 case), a mass with microcalcifications (in 1 case), microcalcifications (in 2 cases) and asymmetry (in 1 case). Three mammograms were negative, including 1 obtained from a patient with extensive comedocarcinoma. Breast ultrasonograms obtained from 4 patients (2 of whom also had mammograms) showed solid hypoechoic masses; in 2 of the ultrasonograms, the masses simulated a benign lesion.

CONCLUSIONS

Although breast cancer during pregnancy and lactation is rare, this study suggests that radiologists should include it in the differential diagnosis of a solid breast mass seen during pregnancy or lactation. Clinicians appear to be reluctant to use breast imaging in these patients; however, this can lead to a delay in diagnosis. Ultrasonography is the modality of choice for initial analysis of such a mass in this age group. Mammography with shielding of the abdomen is recommended if there is suspicion of cancer. Clinical, mammographic and sonographic findings should be integrated for optimum interpretation.

Effects at two years of a low-fat, high-carbohydrate diet on radiologic features of the breast: results from a randomized trial. Canadian Diet and Breast Cancer Prevention Study Group

BACKGROUND

The appearance of breast tissue on mammography varies according to its composition. Fat is radiolucent and appears dark on mammography, while stromal and epithelial tissue has greater optical density and appears light. Extensive areas of radiologically dense breast tissue seen on mammography are associated with an increased risk of breast cancer.

PURPOSE

The purpose of the present study was to determine whether the adoption of a low-fat, high-carbohydrate diet for 2 years would reduce breast density.

METHODS

Women with radiologic densities in more than 50% of the breast area on mammography were recruited and randomly allocated to an intervention group taught to reduce intake of dietary fat (mean, 21% of calories) and increase complex carbohydrate (mean, 61% of calories) or to a control group (mean, 32% of calories from fat and 50% of calories from carbohydrates). Mammographic images from 817 subjects were taken at baseline and compared with those taken 2 years after random allocation by use of a quantitative image analysis system, without knowledge of the dietary group of the subjects or of the sequence in which pairs of images had been taken. The effects of the intervention on the mammographic features of breast area, area of dense tissues in the breast, and the percent of the breast occupied by dense tissue were examined using t tests. Multiple regression was used to examine these effects while accounting for age at trial entry, weight change, and menopausal status.

RESULTS

After 2 years, the total area of the breast was reduced by an average of 233.7 mm2 (2.4%) (95% confidence interval [CI] = 106.9-360.6) in the intervention group compared with an average increase of 26.3 mm2 (0.3%) (95% CI = -108.0-160.5) in the control group (P = .01). The area of density was reduced by 374.4 mm2 (6.1%) (95% CI = 235.1-513.8) in the intervention group compared with an average of 127.7 mm2 (2.1%) (95% CI = 8.6-246.7) in the control group (P = .01). Weight loss was associated with a reduction in breast area. The effect of the intervention on breast area was only marginally statistically significant after weight change, menopausal status, and age at trial entry were taken into account (P = .06). Greater weight loss and becoming postmenopausal were associated with statistically significant reductions in the area of density on the mammographic image at 2 years (P = .04 and P<.001, respectively). Age at entry into the trial was marginally significant in the same direction (P = .06). The effect of the intervention on area of density remained statistically significant after controlling for weight loss, age at entry, and menopausal status (P = .03). The change in the percentage of dense tissue in the mammographic image was not significantly different between the two groups (P = .71).

CONCLUSIONS AND IMPLICATIONS

These results show that after 2 years, a low-fat, high-carbohydrate diet reduced the area of mammographic density, a radiographic feature of the breast that is a risk factor for breast cancer. Longer observation of a larger number of subjects will be required to determine whether these effects are associated with changes in risk of breast cancer.

Plasma lipids, lipoproteins, and mammographic densities

There is strong evidence that the risk of breast cancer in populations is influenced by environmental factors. Plasma lipids and lipoproteins are known to be under environmental control and to have epidemiological and/or biological characteristics that suggest they may be relevant to breast cancer risk. The purpose of the study described here was to determine whether plasma lipids, lipoproteins, and the urinary excretion of the mutagen malondialdehyde (MDA) are associated with differences in breast cancer risk. We measured plasma lipids, lipoproteins, and urinary MDA in women without breast cancer but with different degrees of density of the breast parenchyma on mammography, a strong risk factor for breast cancer. Mammograms from 273 premenopausal women were digitized to high spatial resolution by a scanning densitometer, and images were analyzed to quantify the extent of density. The percentage of the breast occupied by mammographic densities was found, after controlling for the effects of age and the Quetelet index of obesity, to be significantly associated with plasma levels of high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglyceride, apoprotein B, and urinary excretion of MDA. A multivariate model comprised of the Quetelet index of obesity, alcohol consumption, apoprotein B, parity, daily MDA excretion, and the skinfold thickness sum accounted for 36% of the variation in breast density. These results suggest that differences in lipid metabolism are associated with differences in breast cancer risk as defined by mammographic densities. These findings are consistent with several other observations that show a relationship between plasma lipids, lipoproteins, and risk factors for breast cancer.

Rapid modulation of liver-specific transcription factors after injury

BACKGROUND

The reaction to injury is a well-orchestrated physiologic response involving the coordinated actions of multiple integrated systems. It initially occurs at the molecular level and involves changes in gene transcription. We hypothesized that the molecular mechanisms regulating the generation of an inflammatory response are similar to those orchestrating developmental and tissue-specific expression of proteins and, in the case of the acute phase response, occur through manipulation of liver-specific transcription factors and their binding activity.

METHODS

Female BALB/c mice, 7 to 8 weeks old, were subjected to a 15% body surface area burn. Total and polyadenylated liver RNA was isolated, and Northern blot analysis was performed to determine the kinetics of the acute phase proteins albumin and fibrinogen and the liver-specific transcriptional factors CCAAT-enhancer binding protein (C/EBP) alpha, hepatocyte nuclear factor (HNF)-1 alpha, and HNF-4.

RESULTS

Induction of the injury response was shown by an increase in fibrinogen messenger RNA levels and a decrease in albumin mRNA levels. The liver-specific transcription factor C/EBP alpha decreased after injury and remained significantly lower than control at 3 hours. HNF-4 mRNA levels fell more slowly, reaching significantly lower levels at 6 hours and remaining suppressed at 34 hours. HNF-1 alpha showed the most rapid fall in mRNA levels at 30 minutes after injury and remained significantly below control levels at 34 hours.

CONCLUSIONS

The minimal burn injury model leads to the molecular induction of the acute phase response and induces significant and rapid changes in the liver-specific transcription factors C/EBP alpha, HNF-1 alpha, and HNF-4. These changes may represent a mechanism through which the organ-specific response to injury is mediated.

Technology transfer in digital mammography. Report of the Joint National Cancer Institute-National Aeronautics and Space Administration workshop of May 19-20, 1993

Digital mammography is one of the most promising novel technologies for further improvement of early detection of breast cancer, offering important potential advantages: 1) improved image quality; 2) digital image processing for improved lesion contrast; 3) computer-aided diagnosis for enhanced radiologic interpretation; and 4) teleradiology for facilitated radiologic consultation. The Diagnostic Imaging Research Branch of the National Cancer Institute (NCI) recently funded an international, multidisciplinary, multi-institutional Digital Mammography Development Group for collaborations between NCI, the academic community, and industry to facilitate the integrated development and implementation of digital mammographic systems. Currently, however, digital mammography faces a number of fundamental technological roadblocks: 1) cost-effective digital detectors and displays for imaging systems; 2) the need for novel algorithms for image processing and computer-aided diagnosis; and 3) high performance, low cost digital networks to provide an "information superhighway" for teleradiology. To solve some of these technological problems, the Diagnostic Imaging Research Branch of NCI joined efforts with the Technology Transfer Division of the National Aeronautics and Space Administration to pursue a federal technology transfer program in digital mammography. The authors discuss the findings and recommendations of the workshop entitled "Technology Transfer in Digital Mammography," which was organized and held jointly by the NCI and the National Aeronautics and Space Administration in May, 1993. Numerous innovative technologies of varying degree of promise for digital mammography were presented at the conference. In this article, specific technologies presented at the workshop by the federal and federally-supported laboratories are described, and critiques of these technologies by the leaders of the medical imaging community are presented.

Scattered radiation in fan beam imaging systems

Scatter-to-primary energy fluence ratios (S/P) have been studied for fan x-ray beams as used in CT scanners and slit projection radiography systems. The dependence of S/P on phantom diameter, distance from phantom to image receptor, and kilovoltage is presented. An empirical equation is given that predicts S/P over a wide range of fan beam imaging configurations. For CT body scans on a 4th-generation machine, S/P is approximately 5%. Scattered radiation can produce a significant cupping artefact in CT images which is similar to that due to beam hardening. When multiple slices are used in scanned slit radiography, they can be arranged such that the increase in S/P is negligible. Calculations of scatter-to-primary ratios for first order scattering showed that for fan beams the contribution of coherent scatter is comparable to or greater than that of incoherent first scatter.

Spectroscopy of diagnostic x rays by a Compton-scatter method

A method is described for measuring the energy spectra of diagnostic x rays using a high-resolution intrinsic germanium spectrometer. The method is applicable over the wide range of x-ray exposure rates normally used in radiography. Reduction of the high x-ray beam intensity to a level acceptable to the germanium spectrometer is achieved by measuring the spectrum of photons scattered through 90 degrees by a lucite disc. From this measured spectrum the primary spectrum is obtained by calculation. Some typical x-ray spectra are presented.