Who is prone to high levels of distress after prophylactic mastectomy and/or salpingo-ovariectomy?

BACKGROUND: The present study aimed to assess predictors of distress after 'prophylactic mastectomy (PM) and salpingo-ovariectomy (PSO), in order to enable the early identification of patients who could benefit from psychological support. PATIENTS AND METHODS: General distress and cancer-related distress were assessed in 82 women at increased risk of hereditary breast and/or ovarian cancer undergoing PM and/or PSO, before and 6 and 12 months after prophylactic surgery. Neurotic lability and coping were assessed before surgery. RESULTS: Cancer-related distress and general distress at both follow-up moments were best explained by the level of cancer-related and general distress at baseline. Being a mutation carrier was predictive of increased cancer-related distress at 6-month follow-up (but not at 12 months), and of lower general distress 12 months after prophylactic surgery. Also, coping by having comforting thoughts was predictive of less cancer-related distress at 6-month follow-up. CONCLUSIONS: Genetically predisposed women who are at risk of post-surgical distress can be identified using one or more of the predictors found in this study. Exploration of and/or attention to cancer-related distress and coping style before prophylactic surgery may help physicians and psychosocial workers to identify women who might benefit from additional post-surgical support.

Tumour characteristics, survival and prognostic factors of hereditary breast cancer from BRCA2-, BRCA1- and non-BRCA1/2 families as compared to sporadic breast cancer cases.

AIM OF THE STUDY: Results on tumour characteristics and survival of hereditary breast cancer (BC), especially on BRCA2-associated BC, are inconclusive. The prognostic impact of the classical tumour and treatment factors in hereditary BC is insufficiently known. METHODS: We selected 103 BRCA2-, 223 BRCA1- and 311 non-BRCA1/2 BC patients (diagnosis 1980-2004) from the Rotterdam Family Cancer Clinic. To correct for longevity bias, analyses were also performed while excluding index patients undergoing DNA testing 2 years after BC diagnosis. As a comparison group, 759 sporadic BC patients of comparable age at and year of diagnosis were selected. We compared tumour characteristics, the occurrence of ipsilateral recurrence (LRR) and contralateral BC (CBC) as well as distant disease-free (DDFS), BC-specific (BCSS) and overall survival (OS) between these groups. By multivariate modelling, the prognostic impact of tumour and treatment factors was investigated separately in hereditary BC. RESULTS: We confirmed the presence of the particular BRCA1-phenotype. In contrast, tumour characteristics of BRCA2-associated BC were similar to those of non-BRCA1/2 and sporadic BC, with the exception of a high risk of CBC (3.1% per year) and oestrogen-receptor (ER)-positivity (83%). No significant differences between BRCA2-associated BC and other BC subgroups were found with respect to LRR, DDFS, BCSS and OS. Independent prognostic factors for BC-specific survival in hereditary BC (combining the three subgroups) were tumour stage, adjuvant chemotherapy, histologic grade, ER status and a prophylactic (salpingo-)oophorectomy. CONCLUSIONS: Apart from the frequent occurrence of contralateral BC and a positive ER-status, BRCA2-associated BC did not markedly differ from other hereditary or sporadic BC. Our observation that tumour size and nodal status are prognostic factors also in hereditary BC implies that the strategy to use these factors as a proxy for ultimate mortality appears to be valid also in this specific group of patients.

Family system characteristics and psychological adjustment to cancer susceptibility genetic testing: a prospective study.

This study examined prospectively the contribution of family functioning, differentiation to parents, family communication and support from relatives to psychological distress in individuals undergoing genetic susceptibility testing for a known familial pathogenic BRCA1/2 or Hereditary nonpolyposis colorectal cancer-related mutation. Family functioning, differentiation to parents, hereditary cancer-related family communication and perceived support from relatives were assessed in 271 participants for genetic testing before test result disclosure. Hereditary cancer distress (assessed by the Impact of Event Scale) and cancer worry (assessed by the Cancer Worry Scale) were assessed before, 1 week after, and 6 months after test result disclosure. Participants reporting more cancer-related distress over the study period more frequently perceived the communication about hereditary cancer with relatives as inhibited, the nuclear family functioning as disengaged-rigid or enmeshed-chaotic, the support from partner as less than adequate and the relationship to mother as less differentiated. Especially, open communication regarding hereditary cancer and partner support may be important buffers against hereditary cancer distress. Identifying individuals with insufficient sources of support and addressing the family communication concerning hereditary cancer in genetic counseling may help the counselee to adjust better to genetic testing.

Passive coping and psychological distress in women adhering to regular breast cancer surveillance.

Since 2000 the MRISC study evaluates the psychological consequences of regular breast cancer surveillance for women at increased risk for hereditary breast cancer. Coping style may influence these psychological consequences. In a cohort of 357 women at increased risk for hereditary breast cancer, the impact of coping styles on the course, divided into level and trend of psychological distress (general and breast cancer specific) was examined, around two consecutive surveillance appointments. With structural equation modelling we found passive coping to be associated with higher levels of both general and breast cancer specific distress. Seeking social support, expression of emotions and thinking comforting thoughts were associated with lower levels of psychological distress. Coping style was not associated with the trend of psychological distress around the two surveillance appointments. It is recommendable to take coping styles into account when counselling these high-risk women.

Tumor characteristics and detection method in the MRISC screening program for the early detection of hereditary breast cancer.

In the MRISC study, women with an inherited risk for breast cancer were screened by a 6-month clinical breast examination (CBE) and yearly MRI and mammography. We found that the MRISC screening scheme could facilitate early breast cancer diagnosis and that MRI was a more sensitive screening method than mammography, but less specific. In the current study we investigated the contribution of MRI in the early detection of breast cancer in relation to tumor characteristics. From November 1999 to October 2003, 1909 women were included and 50 breast cancers were detected, of which 45 were evaluable and included in the current study. We compared the characteristics of tumors detected by MRI-only with those of all other (non-palpable) screen-detected tumors. Further, we compared the sensitivity of mammography and MRI within subgroups according to different tumor characteristics. Twenty-two (49%) of the 45 breast cancers were detected by MRI and not visible at mammography, of which 20 (44%) were also not palpable (MRI-only detected tumors). MRI-only detected tumors were more often node-negative than other screen-detected cancers (94 vs. 59%; P=0.02) and tended to be more often

The course of distress in women at increased risk of breast and ovarian cancer due to an (identified) genetic susceptibility who opt for prophylactic mastectomy and/or salpingo-oophorectomy.

The levels and course of psychological distress before and after prophylactic mastectomy (PM) and/or prophylactic salpingo-oophorectomy (PSO) were studied in a group of 78 women. General distress was measured through the hospital anxiety and depression scale (HADS), cancer-related distress using the impact of events scale (IES). Measurement moments were baseline (2-4 weeks prior to prophylactic surgery), and 6 and 12 months post-surgery. After PM, anxiety and cancer-related distress were significantly reduced, whereas no significant changes in distress scores were observed after PSO. At one year after prophylactic surgery, a substantial amount of women remained at clinically relevant increased levels of cancer-related distress and anxiety. We conclude that most women can undergo PM and/or PSO without developing major emotional distress. More research is needed to further define the characteristics of the women who continue to have clinically relevant increased scores after surgery, in order to offer them additional counselling.

Association between the CHEK2*1100delC germ line mutation and estrogen receptor status.

Already published data were further analyzed regarding the association between the CHEK2*1100delC germ line mutation and estrogen receptor (ER) status in patients with breast cancer. The CHEK2*1100delC mutation was more prevalent among the patients with a positive ER status (4.2% versus 1.0%). An ER-negative status was beside CHEK2*1100delC mutation and independently associated with an earlier of age onset of breast cancer. There was a trend that an ER-negative status, beside the presence of a CHEK2*1100delC mutation, was associated with a worse disease-free survival. There might be an association between ER status and a CHEK2*1100delC mutation. More studies with larger number of patients are needed to further investigate the relation between CHEK2*1100delC and ER status.

Experience of parental cancer in childhood is a risk factor for psychological distress during genetic cancer susceptibility testing.

BACKGROUND: This study explores the effect of age at the time of parental cancer diagnosis or death on psychological distress and cancer risk perception in individuals undergoing genetic testing for a specific cancer susceptibility. PATIENTS AND METHODS: Cancer-related distress, worry and risk perception were assessed in 271 applicants for genetic testing of an identified mutation in BRCA1/2 (BReast CAncer) or a HNPCC (Hereditary Nonpolyposis Colorectal Cancer) related gene before, one week after, and six months after genetic test disclosure. The course of distress and risk perception were compared between individuals having witnessed parental cancer or loss due to cancer in childhood, adolescence, adulthood and having unaffected parents. RESULTS: Individuals with parental cancer in childhood (under age 13) reported the highest level of cancer related distress, worry and risk perception. Women having their mother affected by breast cancer in puberty (aged 10-13 years) perceived higher breast cancer risks than women with an affected mother in adulthood or without an affected mother. Individuals with an affected parent perceived cancer risks as higher than individuals without an affected parent, but were not more distressed. CONCLUSIONS: Experience of parental cancer in childhood is a risk factor for psychological distress during the genetic testing process.

Trends in endocrine therapy and chemotherapy for early breast cancer: a focus on the premenopausal patient.

PURPOSE: The majority of breast cancers are diagnosed at an early stage, and treatment is focused on cure and prolonging disease-free survival. Local therapy (surgery and/or radiation treatment) is standard, along with systemic adjuvant therapy that may effectively prevent or delay relapse and death in early-stage disease. In premenopausal women, adjuvant therapeutic approaches include combination cytotoxic chemotherapy and endocrine therapy. Cyclophosphamide, methotrexate and 5-fluorouracil (CMF) was the established chemotherapy regimen; however, newer regimens have more recently been introduced that may offer some benefit over CMF including anthracycline-containing regimens [e.g. cyclophosphamide, epirubicin and 5-fluorouracil (CEF)], and taxane-containing regimens. For women with oestrogen receptor (ER)-positive disease, a second option is endocrine therapy that aims to suppress mitogenic oestrogen signalling. Until recently, 5 years of tamoxifen was regarded as the standard adjuvant endocrine treatment in ER-positive disease. Ovarian ablation is also effective in premenopausal women, and can be achieved by surgery, radiotherapy, or via the use of a luteinising hormone-releasing hormone analogue such as goserelin. Combining tamoxifen and goserelin treatment provides more effective oestrogen blockade than either drug alone. However, as the third-generation aromatase inhibitors (AIs) have demonstrated improved efficacy over tamoxifen in postmenopausal women with early and advanced disease, combination treatment with goserelin plus an AI may provide optimal oestrogen blockade in premenopausal patients. CONCLUSIONS: This review assesses the relative merits of chemotherapeutic and endocrine approaches for the treatment of early breast cancer, and summarises relevant ongoing clinical trials, with an emphasis on the premenopausal setting.

Survival and prognostic factors in BRCA1-associated breast cancer.

BACKGROUND: Studies comparing survival in BRCA1-associated and sporadic breast cancer (BC) report inconsistent results and frequently concern small sample sizes. Further, the prognostic impact of the classical tumour and treatment factors is unclear in BRCA1-associated BC. PATIENTS AND METHODS: We selected 223 BC patients diagnosed between 1980 and 2001 within families with a deleterious germline BRCA1-mutation ascertained at the Rotterdam Family Cancer Clinic. To correct for ascertainment bias, the group of index patients undergoing DNA testing more than 2 years after BC diagnosis (n = 53) was separated from the other BRCA1-patients (n = 170). All BRCA1-associated patients were matched in a 1:2 ratio for age and year of diagnosis to sporadic BC patients. We compared the occurrence of ipsi- and contralateral BC (CBC) as well as distant disease-free (DDFS), BC-specific (BCSS) and overall survival (OS). By multivariate modelling, the prognostic impact of tumour and treatment factors was investigated separately in BRCA1-associated and sporadic breast cancers. RESULTS: For the total group of 669 cases, the median follow-up was 5.1 years, the median age at diagnosis 39 years. We confirmed the existence of the typical BRCA1-associated tumour type and the high CBC incidence. No significant differences between BRCA1-associated and sporadic tumours were found with respect to ipsilateral BC recurrence (HR(mult) 0.7; P = 0.24), DDFS (HR(mult) 1.2; P = 0.37) or BC-specific survival (HR(mult) 1.3; P = 0.23). A trend towards a worse survival was found for BRCA1-associated ductal BC (HR(mult) 1.5, P = 0.07). Prognostic factors for BRCA1-associated BC were age at diagnosis, tumour size and morphology, and nodal status. Further, survival was non-significantly improved by systemic treatment and a bilateral salpingo-oophorectomy. No effect on survival of a contralateral prophylactic mastectomy was seen. CONCLUSIONS: BRCA1-associated BC is characterised by specific tumour characteristics, a high incidence of CBC and a trend towards a worse survival for the ductal tumour type. Our observation that tumour size and nodal status are also prognostic factors for BRCA1-associated BC implies that the strategy to use these factors as a proxy for ultimate mortality, for instance in BC screening programmes or the consideration of (contralateral) preventive mastectomy, appears to be valid in this specific group of patients.

Laser microdissection and microarray analysis of breast tumors reveal ER-alpha related genes and pathways.

About 70-80% of breast cancers express estrogen receptor alpha (ER-alpha), and estrogens play important roles in the development and growth of hormone-dependent tumors. Together with lymph node metastasis, tumor size, and histological grade, ER status is considered as one of the prognostic factors in breast cancer, and an indicator for hormonal treatment. To investigate genes and pathways that are associated with ER status and epithelial cells in breast tumor, we applied laser capture microdissection (LCM) technology to capture epithelial tumor cells from 28 lymph node-negative breast tumor samples, in which 17 patients had ER-alpha+ tumors, and 11 patients have ER-alpha- tumors. Gene expression profiles were analysed on Affymetrix Hu133A GeneChip. Meanwhile, gene profiles using total RNA isolated from bulk tumors of the same 28 patients were also generated. In total, 146 genes and 112 genes with significant P-value and having significant differential expression between ER-alpha+ and ER-alpha- tumors were identified from the LCM data set and bulk tissue data set, respectively. A total of 61 genes were found to be common in both data sets, while 85 genes were unique to the LCM data set and 51 genes were present only in the bulk tumor data set. Pathway analysis with the 85 genes using Gene Ontology suggested that genes involved in endocytosis, ceramide generation, Ras/ERK/Ark cascade, and JAT-STAT pathways may play roles related to ER. The gene profiling with LCM-captured tumor cells provides a unique approach to study epithelial tumor cells and to gain an insight into signaling pathways associated with ER.

[Preventive surgical prcedures for inherited risk of breast cancer]. / Preventief chirurgisch ingrijpen bij erfelijke belasting voor borstkanker.

Preventive surgical procedures for inherited risk of breast cancer Forwomen with a demonstrated BRCA1 or BRCA2 mutation, the cumulative risk of developing invasive breast cancer before the age of 70 years is about 50-85% and the risk of developing invasive epithelial ovarian cancer is 20-60%. Regular surveillance including physical examination and imaging is offered to mutation carriers and the options for risk-reducing surgery are discussed. Although bilateral prophylactic mastectomy is a drastic intervention, it significantly reduces the incidence of breast cancer. For mutation carriers with breast cancer, the decision to combine risk-reducing surgery with treatment is determined by the TNM stage of the disease. Prophylactic bi- or contralateral mastectomy after previous treatment for unilateral breast cancer reduces the incidence of contralateral breast cancer, but has no impact on survival. The complexity of the problem demands a multidisciplinary approach within the context of a family cancer clinic.

Cancer risks in BRCA2 families: estimates for sites other than breast and ovary.

BACKGROUND: In BRCA2 mutation carriers, increased risks have been reported for several cancer sites besides breast and ovary. As most of the families included in earlier reports were selected on the basis of multiple breast/ovarian cancer cases, it is possible that risk estimates may differ in mutation carriers with a less striking family history. METHODS: In the Netherlands, 139 BRCA2 families with 66 different pathogenic mutations were included in a nationwide study. To avoid testing bias, we chose not to estimate risk in typed carriers, but rather in male and female family members with a 50% prior probability of being a carrier (n = 1811). The relative risk (RR) for each cancer site with the exception of breast and ovarian cancer was determined by comparing observed numbers with those expected, based on Dutch cancer incidence rates. RESULTS: We observed an excess risk for four cancer sites: pancreas (RR 5.9; 95% confidence interval (CI) 3.2 to 10.0), prostate (2.5; 1.6 to 3.8), bone (14.4; 2.9 to 42.1) and pharynx (7.3; 2.0 to 18.6). A small increase was observed for cancer of the digestive tract (1.5; 1.1 to 1.9). Histological verification was available for 46% of the tumours. Nearly all increased risks reached statistical significance for men only. Cancer risks tended to be higher for people before the age of 65 years. Moreover, families with mutations outside the previously defined ovarian cancer cluster region tended to have a higher cancer risk. CONCLUSIONS: We found that BRCA2 carriers are at increased risk for cancers of the prostate and pancreas, and possibly bone and pharynx. Larger databases with extended follow up are needed to provide insight into mutation specific risks of selected carriers in BRCA2 families.

[The value of gene expression profiles using micoarrays for the individualisation of adjuvant therapy after surgery for breast cancer]. / De waarde van genexpressieprofielen vastgesteld met microarrays voor het individualiseren van adjuvante therapie bij patiënten na chirurgische behandeling wegens mammacarcinoom.

Gene-expression profiles are a promising development in determining the prognosis of patients with primary breast cancer. They accurately assess the risk on distant recurrence of disease and show if the patient might benefit from adjuvant therapy after surgery thus minimising the risk of distant metastases. Three clinically relevant profiles on prognosis have now been published, two of which come from the Netherlands, and whose results are an improvement on those using traditional clinical parameters i.e. the St. Gallen and the National Institutes of Health criteria. These gene-expression profiles mean that 25-40% of patients need no longer undergo adjuvant systemic therapy (chemotherapy and/or endocrine therapy). Although the risk-stratifying power of these profiles has been established, their power in predicting the response of the patients to adjuvant systemic therapy still awaits scientific proof.

Effects of tamoxifen and octreotide LAR on the IGF-system compared with tamoxifen monotherapy.

The insulin-like growth factor (IGF)-system was evaluated in 150 breast cancer patients participating in a randomised phase III trial comparing octreotide pamoate and tamoxifen with tamoxifen+placebo. Alterations in the IGF-system in the two treatment arms and individual changes with respect to outcome were compared. Serum IGF-I and -II, free IGF-I, and insulin-like growth factor binding protein 1-3 (IGFBP1-3) were measured by radioimmmunoassay (RIA)/immunoradiometric assay (IRMA) and IGFBPs by Western ligand blots (WLB) before and during treatment. Combined treatment caused a higher increase in IGFBP-1 and larger suppression of total and free IGF-I, IGF-II, and IGFBP-3 (P<0.01 for all), but less suppression of IGFBP-2 (P<0.05) compared with tamoxifen monotherapy. An increase in IGFBP-2 25% was associated with decreased progression-free survival (PFS) in the total patient population and combined treatment group. Similar response rates and time to progression in the treatment arms suggests moderate suppression of circulating IGF-I has no influence on clinical outcome.

Effect of combination therapy with aminoglutethimide and hydrocortisone on prostate-specific antigen response in metastatic prostate cancer refractory to standard endocrine therapy.

A prospective study was performed to investigate the combination of the aromatase inhibitor aminoglutethimide and hydrocortisone in androgen-independent prostate cancer with changes in prostate-specific antigen (PSA) level as main determinant for response. Thirty-five patients were treated with aminoglutethimide 1000 mg daily and hydrocortisone acetate 40 mg daily. PSA measurements were performed every month. If evaluable lesions were present, objective tumor assessment was done by computed tomography scan and X-ray investigations. In 12 patients (37%) the PSA value showed a confirmed response with a decline in serum level of at least 50%. Median time to progression in responding and all patients was 10.5 and 4.5 months, respectively. Median duration of response in responding patients was 9 months. Median survival for these two groups was 23 and 14.5 months, respectively. Of seven patients with measurable disease, two showed a partial response and five a stable disease. Improvement in general condition, pain and feeling of well-being was noted in two-thirds of patients. Therapy was well tolerated with mainly grade I and II adverse events in 20% of patients. We conclude that aminoglutethimide is a valuable second-line therapy for patients with androgen-independent prostate cancer.

Tumour characteristics and prognosis of breast cancer patients carrying the germline CHEK2*1100delC variant.

BACKGROUND: The germline CHEK2*1100delC variant has been associated with breast cancer in multiple case families where involvement of BRCA1 and BRCA2 has been excluded. METHODS: We have investigated the tumour characteristics and prognosis of carriers of this germline variant by means of a prospective cohort study in an unselected cohort of 1084 consecutive patients with primary breast cancer. Data were collected for 34 patients with a germline CHEK2*1100delC mutation and for 102 patients without this mutation, stratified by age and date of diagnosis of the first primary breast cancer (within 1 year). RESULTS: Carriers developed steroid receptor positive tumours (oestrogen receptor (ER): 91%; progesterone receptor (PR): 81%) more frequently than non-carriers (ER: 69%; PR: 53%; p = 0.04). Mutation carriers more frequently had a female first or second degree relative with breast cancer (p = 0.03), or had any first or second degree relative with breast or ovarian cancer (p = 0.04). Patients with the CHEK2 variant had a more unfavourable prognosis regarding the occurrence of contralateral breast cancer (relative risk (RR) = 5.74; 95% confidence interval (CI) 1.67 to 19.65), distant metastasis-free survival (RR = 2.81; 95% CI 1.20 to 6.58), and disease-free survival (RR = 3.86; 95% CI 1.91 to 7.78). As yet, no difference with respect to overall survival has been found at a median follow up of 3.8 years. CONCLUSION: We conclude that carrying the CHEK2*1100delC mutation is an adverse prognostic indicator for breast cancer. If independently confirmed by others, intensive surveillance, and possibly preventive measures, should be considered for newly diagnosed breast cancer cases carrying the CHEK2*1100delC variant.

Impact of screening for breast cancer in high-risk women on health-related quality of life.

The effectiveness of intensive surveillance in women at high risk for breast cancer due to a familial or genetic predisposition is uncertain and is currently being evaluated in a Dutch magnetic resonance imaging (MRI) screening (MRISC) study, in which annual imaging consists of mammography and MRI. Unfavourable side effects on health-related quality of life may arise from this screening process. We examined the short-term effects of screening for breast cancer in high-risk women on generic health-related quality of life and distress. A total of 519 participants in the MRISC study were asked to complete generic health-status questionnaires (SF-36, EQ-5D) as well as additional questionnaires for distress and items relating to breast cancer screening, at three different time points around screening. The study population showed significantly better generic health-related quality of life scores compared to age-/sex-adjusted reference scores from the general population. Neither generic health-related quality of life scores nor distress scores among the study sample (n=334) showed significant changes over time. The impact of the screening process on generic health status did not differ between risk categories. Relatively more women reported mammography as quite to very painful (30.1%) compared to MRI. Anxiety was experienced by 37% of the women undergoing MRI. We conclude that screening for breast cancer in high-risk women does not have an unfavourable impact on short-term generic health-related quality of life and general distress. In this study, high-risk women who opted for regular breast cancer screening had a better health status than women from the general population.

Ipsilateral breast tumour recurrence in hereditary breast cancer following breast-conserving therapy.

The overall rate of an ipsilateral breast tumour recurrence (IBTR) after breast-conserving therapy (BCT) ranges from 1% to 2% per year. Risk factors include young age but data on the impact of BRCA1/2 mutations or a definite positive family history for breast cancer are scarce. We investigated IBTR after BCT in patients with hereditary breast cancer (HBC). Through our family cancer clinic we identified 87 HBC patients, including 26 BRCA1/2 carriers, who underwent BCT between 1980 and 1995 (cases). They were compared to 174 patients with sporadic breast cancer (controls) also treated with BCT, matched for age and year of diagnosis. Median follow up was 6.1 years for the cases and 6.0 years for controls. Patient and tumour characteristics were similar in both groups. An IBTR was observed in 19 (21.8%) hereditary and 21 (12.1%) sporadic patients. In the hereditary patients more recurrences occurred elsewhere in the breast (21% versus 9.5%), suggestive of new primaries. Overall, the actuarial IBTR rate was similar at 2 years, but higher in hereditary as compared to sporadic patients at 5 years (14% versus 7%) and at 10 years (30% versus 16%) (P=0.05). Post-relapse and overall survival was not different between hereditary and sporadic cases. Hereditary breast cancer was therefore associated with a higher frequency of early (2-5 years) and late (>5 years) local recurrences following BCT. These data suggest an indication for long-term follow up in HBC and should be taken into account when additional 'risk-reducing' surgery after primary BCT is eventually considered.

Allelotype of 28 human breast cancer cell lines and xenografts.

Heterozygous loss of relatively large chromosomal regions is a hallmark of the inactivation of tumour suppressor genes. Searching for deletions in cancer genomes therefore provides an attractive option to identify new tumour suppressor genes. Here, we have performed a genome-wide survey for regions exhibiting allelic loss in 24 commercially available breast cancer cell lines and four breast cancer xenografts, using microsatellite analysis. The assembled allelotype revealed an average fractional allelic loss of 0.34. A total of 19 arms had low allelic loss frequencies (<25%) and 17 arms had moderate allelic loss frequencies (25-50%). Five chromosomal arms were deleted in more than half of the breast cancer samples (8p, 10q, 13q, 17p, and 17q). Three of these frequently lost chromosomal arms had not been identified as such by comparative genome hybridisation, illustrating the higher sensitivity of microsatellite analysis for the detection of allelic losses. As we present allelic loss data of individual samples, our allelotype should not only aid the identification of new breast cancer genes but also provides a baseline for myriad studies involving these breast cancer cell lines.