R Kaas

Netherlands Cancer Institute, Amsterdamo, North Holland, Netherlands

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Publications (17)29.15 Total impact

  • R Kaas, E J Th Rutgers
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    ABSTRACT: Population screening for breast cancer in the Netherlands in women 50-75 years ofage shows a reduction in mortality in this age group, which is the goal of screening. In a recent statement, the Dutch Cancer Society did not advise breast self-examination for women in general, because a meta-analysis had not shown a reduction in mortality, irrespective of the positive findings on self-examination in many retrospective studies. However, breast self-examination may be advised to a small group of women with familial or hereditary breast cancer, especially carriers of the BRCA1 gene mutation, in whom a high percentage of rapidly proliferating grade III carcinomas are found.
    Nederlands tijdschrift voor geneeskunde 11/2008; 152(43):2317-8.
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    ABSTRACT: To compare the breast cancer stages found during MG alone surveillance in women at increased risk with those detected in a program where MRI was added. Stage results of in a retrospective MG alone study of prospectively followed patients, compared with the pooled stage results of breast cancers MG/MRI surveillance. One hundred and-fifty-one patients were detected with a first or contralateral breast cancer. Interval cancers were diagnosed in 56% of the BRCA1, 42% of the BRCA2 and 28% of the non-BRCA carriers. A considerable proportion of the breast cancers were detected with breast self-examination alone: 41%, 27% and 31% respectively. Nevertheless the established goals for biennial population screening were reached, except for the BRCA2 carriers, but this group was small. Comparison with pooled data from published MG/MRI surveillance studies did not show significant differences in the stages, except for the BRCA2 carriers. Breast cancers detected in a MG alone surveillance program for women at increased risk fulfill most goals set for population screening except for the BRCA2 carriers. Breast self-examination appears to be a valuable additional detection method especially for BRCA1 carriers, who are at risk of developing a highly proliferating breast cancer.
    European journal of surgical oncology: the journal of the European Society of Surgical Oncology and the British Association of Surgical Oncology 06/2008; 34(5):501-7. · 2.56 Impact Factor
  • Ejc Supplements - EJC SUPPL. 01/2008; 6(7):91-91.
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    ABSTRACT: Breast cancers in BRCA1 gene mutation carriers often have specific histologic features: grade III tumors with pushing margins. Our purpose was to compare the mammographic and histologic features of breast cancers in carriers with those in age-matched sporadic controls. The features of breast cancers in 27 BRCA1 carriers found during annual surveillance were compared to those in 107 age-matched sporadic controls. The carriers had no (classic) spiculated mammographic lesions, a high percentage of well-defined masses and hardly any masses with microcalcifications, whereas the controls had significantly fewer well-defined ones and only in 27% spiculated lesions on the mammogram. The well-defined mammographic tumors correlated in 83% of the carriers and in 70% of the controls with histologic circumscribed tumor margins. Spiculated mammographic lesions in the controls were in 90% grade I or II tumors. DCIS with or without infiltration was seen in 22% of the carriers and in 45% of the controls. In conclusion, breast cancers diagnosed in BRCA1 carriers do not have classic malignant mammographic features. A minority of the young sporadic controls show the classic malignant lesion on the mammogram. Both carriers and controls generally show a good correlation between their mammographic- and histologic tumor pattern.
    European Radiology 01/2007; 16(12):2842-8. · 3.55 Impact Factor
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    ABSTRACT: The MRISC study is a screening study, in which women with an increased risk of hereditary breast cancer are screened by a yearly mammography and MRI, and half-yearly clinical breast examination. The sensitivity found in this study was 40% for mammography and 71% for MRI and the specificity was 95 and 90%, respectively. In the current subsequent study we investigated whether these results are influenced by age, a BRCA1/2 mutation, menopausal status and breast density. From November 1999 to October 2003, 1909 eligible women were screened and 50 breast cancers were detected. For the current analysis, data of 4134 screening rounds and 45 detected breast cancers were used. For both imaging modalities, screening parameters, receiver operating characteristic (ROC) curves and uni- and multivariate odds ratios (ORs) were calculated. All analyses were separately performed for age at entry (< 40, 40-49, > or =50), mutation status, menopausal status and breast density. Sensitivity of MRI was decreased in women with high breast density (adjusted OR 0.08). False-positive rates of both mammography (OR(adj) 1.67) and MRI (OR(adj) 1.21) were increased by high breast density, that of MRI by pre-menopausal status (OR(adj) 1.70), young age (OR(adj) 1.58 for women 40-49 years versus women > or =50 years) and decreased in BRCA1/2 mutation carriers (OR(adj) 0.74). In all investigated subgroups the discriminating capacity (measured by the area under the ROC-curve) was higher for MRI than for mammography, with the largest differences for BRCA1/2 mutation carriers (0.237), for women between 40 and 49 years (0.227) and for women with a low breast density (0.237). This report supports the earlier recommendation that MRI should be a standard screening method for breast cancer in BRCA1/2 mutation carriers.
    Breast Cancer Research and Treatment 12/2006; 100(1):109-19. · 4.47 Impact Factor
  • Ejso. 01/2006; 32.
  • Ejc Supplements - EJC SUPPL. 01/2006; 4(2):63-63.
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    ABSTRACT: Randomized clinical trials (RCT) are the best way to define optimal treatment, but the accrual rates for hardly any trials have been reported. We analyzed retrospectively the participation of patients in eight phase III multicenter RTCs. Out of a total of 738 patients treated in a single institution for operable breast cancer over a 3-year period, 455 patients (62%) were eligible for at least one of the ongoing trials. Overall, 81% of the patients were informed and 47% of the eligible patients consented to participate. The accrual was 100% to a study with an aggressive combined modality treatment arm for patients with a poor prognosis. A low accrual rate was seen in two trials: 6% in the "elderly" trial comparing tamoxifen only with mastectomy and 10% to the "axilla" trial comparing surgery with radiotherapy to the axilla. The clinicians failed to inform most of these patients about the two trials. In the literature seven of the eight trials were reported; two of them (29%) failed to accrue enough patients.
    The Breast 09/2005; 14(4):310-6. · 2.49 Impact Factor
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    ABSTRACT: Breast cancers in gene mutation carriers may escape mammographic detection because of rapid growth and tumor expansion. Therefore, they may mimic benign lesions on the mammogram. Twenty-nine BRCA 1/2 mutation carriers under surveillance developed 31 breast cancers between 1994 and 2001 at a mean age of 44.2 years. Controls were 63 women with 67 breast cancers in the same period at a mean age of 53.8 years, also under surveillance because of a life time risk of at least 15%. In 26% of the carriers vs. 48% of the controls, mammography was the method that first suspected a malignancy. Seven radiologists performed a retrospective review of the original mammograms to establish technical assessment, with special attention for circumscribed lesions and estimated probability of malignancy. In the mutation carriers seven (23%) circumscribed non-calcified mammographic masses were found and three in the controls (4.5%) P=0.01. These masses were proven to be malignant. In both groups around 70% of these fast-growing circumscribed lesions were detected by the patients. The masses were situated in breasts with a good interpretable breast pattern. BRCA 1/2 mutation carriers had a significantly higher percentage of circumscribed non-calcified mammographic masses that proved to be malignant. These mammographic lesions in women at high risk should be described as at least Birads 0 and worked-up with ultrasound and needle biopsy.
    European Radiology 10/2004; 14(9):1647-53. · 3.55 Impact Factor
  • Ejc Supplements - EJC SUPPL. 01/2004; 2(3):96-96.
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    ABSTRACT: Adjuvant tamoxifen treatment reduces the occurrence of contralateral breast cancer (CBC). The aim of the study was to investigate the hypothesis that adjuvant tamoxifen reduces the occurrence of oestrogen-receptor (ER)-positive CBC, but not the growth of ER-negative CBCs, and to examine survival after diagnosis of CBC. For the study, ER status was immunohistochemically assessed in CBCs of 35 tamoxifen-treated patients and 115 patients without previous hormonal treatment. Cases were retrieved from a series of patients treated from 1984 to 1995 at nine hospitals. The interval between ipsi- and contralateral breast cancer was at least 1 year. It was seen that the proportion of patients with an ER-negative CBC was significantly higher among those with prior tamoxifen treatment: 37% vs 18% (P=0.047). No difference between the two groups in overall and disease-specific survival following CBC was found. However, the stage differed for both groups: tamoxifen users more often had node-positive contralateral disease (P= 0.045). In conclusion, metachronous CBCs developing after 1-3 years of tamoxifen treatment are more often ER-negative breast cancers. So far this does not seem to have a major impact on survival.
    British Journal of Cancer 04/2003; 88(5):707-10. · 5.08 Impact Factor
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    ABSTRACT: Following treatment for primary breast cancer, annual mammography and regular clinical breast examination is advised. The aim of this study was to investigate whether annual mammography resulted in an improvement in stage of contralateral breast cancers compared with mammography performed at a longer interval. This was a retrospective analysis of patients treated for breast cancer, who developed a contralateral breast cancer between 1977 and 1998. Patients were stratified into two groups according to mammographic interval. Data were available for 275 patients who developed contralateral breast cancer during follow-up. Annual mammography was performed in 51 per cent; these patients were a mean of 5 years younger at diagnosis. Patients who had annual or biennial mammography had comparable rates of impalpable contralateral breast cancer, 30 and 27 per cent respectively. The tumours were of favourable stages in 60 and 58 per cent respectively. Five-year disease-free survival following diagnosis of contralateral breast cancer was 75 per cent in both groups. When the contralateral lesion was detected by mammography, disease-free survival was better, irrespective of the stage of the ipsilateral breast cancer. No difference was found between the two groups in stage distribution and disease-free survival after the diagnosis of contralateral breast cancer. Survival was better in patients in whom the contralateral breast cancer was first detected by mammography.
    British Journal of Surgery 02/2001; 88(1):123-7. · 4.84 Impact Factor
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    ABSTRACT: We report a case of breast carcinoma 6 years after a prophylactic subcutaneous mastectomy. The incidence of breast carcinoma after prophylactic mastectomy is probably less than 2%. If removal of breast tissue is performed to prevent breast cancer, we advocate a complete simple bilateral mastectomy, including nipple-areola complex, axillary tail and pectoral fascia.
    European Journal of Surgical Oncology 09/1998; 24(4):331-2. · 2.61 Impact Factor
  • European Journal of Cancer - EUR J CANCER. 01/1998; 34.
  • European Journal of Cancer - EUR J CANCER. 01/1996; 32:32-32.
  • R Kaas, E J Rutgers
    Nederlands tijdschrift voor geneeskunde 06/1995; 139(20):1053-4.
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    ABSTRACT: Insulin-like growth factor-I (IGF-I) is an important growth factor associated with increased risk of premenopausal breast cancer. We conducted a randomized, placebo-controlled, double-blind, crossover trial to evaluate whether tomato-derived lycopene supplementation (30 mg/day for 2 mo) decreases serum levels of total IGF-I in premenopausal women with 1) a history of breast cancer (n = 24) or 2) a high familial breast cancer risk (n = 36). Also, IGF binding protein (IGFBP) increasing effects were evaluated. Lycopene supplementation did not significantly alter serum total IGF-I and other IGF system components in the 2 study populations combined. However, statistically significant discordant results were observed between the 2 study populations (i.e., P < 0.05 for total IGF-I, free IGF-I, and IGFBP-3). Total IGF-I and IGFBP-3 were increased in the breast cancer survivor population [total IGF-I = 7.0%, 95% confidence interval (CI) = -0.2 to 14.3%; IGFBP-3 = 3.3%, 95% CI = 0.7-6.0%), and free IGF-I was decreased in the family history population (-7.6 %, 95 % Cl = -14.6 to -0.6 %). This randomized controlled trial shows that 2 mo of lycopene supplementation has no effect on serum total IGF-I in the overall study population. However, lycopene effects were discordant between the 2 study populations showing beneficial effects in high-risk healthy women but not in breast cancer survivors.