Spectrum of ATM gene mutations in a hospital-based series of unselected breast cancer patients.

Blood relatives of patients with the inherited disease ataxia telangiectasia (A-T) have an increased susceptibility for breast cancer. We therefore looked for sequence alterations of the ATM gene in a large hospital-based series of unselected breast cancer patients. The whole ATM coding sequence was analyzed in genomic DNA samples from a core group of 192 consecutive breast cancer cases to define the spectrum of ATM gene mutations. Common sequence alterations were then screened in the whole series of 1000 breast cancer patients and in 500 random individuals. In the core group, 21 distinct sequence alterations were identified throughout the ATM coding region, and 1 common splicing mutation was uncovered in intron 10. Almost half of the breast cancer patients (46%) were heterozygotes for 1 of 16 different amino acid substitutions, and three patients (1.6%) carried a truncating mutation. These data indicate that approximately 1 in 50 German breast cancer patients is heterozygous for an A-T-causing mutation. In our extended series, the most common A-T mutation 1066-6T-->G was disclosed in 7 of 1000 (0.7%) breast cancer patients. Transcript analyses indicated that the loss of exon 11 in the ATM mRNA was the pathogenic consequence of this splicing mutation, which produced a <10% of full-length ATM mRNA and ATM protein in a homozygous A-T patient. We also found an excess of rare missense substitutions in the breast cancer cohort compared with random individuals (7.9% versus 5.3% of alleles; odds ratio = 1.6; P < 0.01). One missense substitution, S707P in exon 15, was two times more frequent in breast cancer patients (odds ratio = 2.4; 95% confidence interval, 1.0-5.8) and five times more frequent in patients with bilateral disease than in random individuals (P < 0.001). We conclude that a large variety of distinct ATM mutations and variants exist among breast cancer patients, some of which can contribute to the etiology and progression of the malignancy. Screening for frequent A-T mutations such as the 1066-6-->G splice site substitution can be effective to prospectively identify A-T heterozygotes in an unselected cancer patient population.

[Improvement of breast cancer grading in punch biopsies: grading with the Ki-67 marker]. / Mammakarzinomgraduierung an Gewebestanzen: Objektivierung mit dem Proliferationsmarker Ki-67.

The grading of invasive breast cancers according to Bloom and Richardson (Nottingham modification) provides one of the most important prognostic factors in addition to size and the status of the lymph nodes. Diagnostic reproducibility has been problematic in daily practice as the required criteria for selection and extent of the grading area are frequently not present in the punch biopsies.A total of 346 cases were retrospectively used to compare routine grading from surgical preparations with an equivalently small sample from punch biopsies. In addition, a modified grading of these small samples was developed with Ki-67 immunochemistry and the measurement of core size. In the case of modified grading, 1-3 points were given for Ki-67 and average maximum core diameter. Tubule development was evaluated with 1 or 2 points. A comparison for recurrence free survival and total survival showed significant prognostic differences between 3-5 points (low risk) and 6-8 points (high risk) in uni- and multivariate analyses. The evaluation criteria for Nottingham-Bloom-Richardson grading in a small tissue sample, such as that from a punch biopsy, can hardly be fulfilled. In our series, prognostic value was only found for nodal negative cases. After modification using objective parameters such as nuclear size measurement and Ki-67 proliferation index, a small tissue sample can prove to be of significant prognostic value for nodal negative as well as nodal positive cases.