Analysis of rare disruptive germline mutations in 2,135 enriched BRCA-negative breast cancers excludes additional high-impact susceptibility genes

BACKGROUND

Breast cancer has a significant heritable basis, of which approximately 60% remains unexplained. Testing for BRCA1/BRCA2 offers useful discrimination of breast cancer risk within families, and identification of additional breast cancer susceptibility genes could offer clinical utility.

PATIENTS AND METHODS

We included 2,135 invasive breast cancer cases recruited via the BOCS study, a retrospective UK study of familial breast cancer.

ELIGIBILITY CRITERIA

female, BRCA-negative, white European ethnicity, and one of: i) breast cancer family history, ii) bilateral disease, iii) young age of onset (<30 years), iv) concomitant ovarian cancer. We undertook exome sequencing of cases and performed gene-level burden testing of rare damaging variants against those from 51,377 ethnicity-matched population controls from gnomAD.

RESULTS

159/2135 (7.4%) cases had a qualifying variant in an established breast cancer susceptibility gene, with minimal evidence of signal in other cancer susceptibility genes. Known breast cancer susceptibility genes PALB2, CHEK2 and ATM were the only genes to retain statistical significance after correcting for multiple testing. Due to the enrichment of hereditary cases in the series, we had good power (>80%) to detect a gene of BRCA1-like risk (odds ratio = 10.6) down to a population minor allele frequency of 4.6 x 10^-5 (1 in 10,799, less than one tenth that of BRCA1)and of PALB2-like risk (odds ratio = 5.0) down to a population minor allele frequency of 2.8 x 10^-4 (1 in 1,779, less than half that of PALB2). Power was lower for identification of novel moderate penetrance genes (odds ratio = 2-3) like CHEK2 and ATM.

CONCLUSIONS

This is the largest case-control whole-exome analysis of enriched breast cancer published to date. Whilst additional breast cancer susceptibility genes likely exist, those of high penetrance are likely to be of very low mutational frequency. Contention exists regarding the clinical utility of such genes.

Association of topoisomerase-1 (Topo1) with the efficacy of chemotherapy in a randomized trial for advanced colorectal cancer patients (FOCUS)

10009

Background: We have assessed potential predictive markers of the efficacy of irinotecan and oxaliplatin in advanced CRC patients randomized to fluorouracil (FU), FU+irinotecan (Ir) or FU+oxaliplatin (Ox). Methods: Pathology specimens were retrieved from 1281 patient in the FOCUS trial (ASCO 05 #3518). Normal and tumor DNA were extracted and tissue microarrays were made for immunohistochemistry (IHC). The following factors were assessed for effect on failure-free survival (FFS) with first-line therapy: IHC for MLH1, MSH2, P53, Topo1, ERCC1, MGMT, and COX2; DNA polymorphisms in GSTP1 (105Val), ABCB1 (C3435T), XRCC1 (Q399R), ERCC2 (K751Q), and UGT1A1*28. Results: Among 823 patients assessable for Topo1 IHC, we observed highly significant heterogeneity (interaction) of treatment effect in relation to Topo1 staining intensity (p=0.008, see table). 489 patients (59%) had moderate or high Topo1 expression; these patients derived highly significant benefit from 1st-line chemotherapy with either Ir or Ox. In contrast, the 334 (41%) patients with low Topo1 IHC expression showed no evidence of benefit from the addition of either Ir or Ox compared with FU alone (HR 1 and 0.9 respectively). When patients receiving FU alone are considered separately, low Topo1 expression was associated with significantly better FFS (HR 0.7 (0.6–0.9)). The other 11 molecular markers showed no significant interactions with treatment received (p values for interaction all > 0.1). Conclusions: We have identified a subgroup of 41% patients (with low Topo1 expression) for whom treatment outcome with FU alone is superior, but who appear to gain no benefit from the addition of Ir or Ox. We believe this to be the first demonstration in a large randomized trial of a genuinely predictive molecular marker. If verified in an independent dataset, this information could be used to select patients who can be safely treated with FU alone, or together with alternative additional agents.

[Table: see text]

No significant financial relationships to disclose.

Prognostic value of thymidylate synthase (TS) expression on failure-free survival of fluorouracil-treated metastatic colorectal cancer patients

10011

Background: We previously presented (ASCO 04 #9506) an exploratory analysis of 13 molecular markers in relation to clinical outcomes in 846 patients treated with fluorouracil (FU), or FU+irinotecan, or FU+oxaliplatin in a large UK-based randomized controlled trial (FOCUS - ASCO ’05 #3518). High TS IHC expression and tumor grade were highly significantly associated with reduced failure-free survival (FFS) in a multivariable model. We now present data from an independent validation set of 449 FOCUS patients and on the combined test and validation sets. Methods: Formalin-fixed, paraffin embedded blocks were retrieved from consenting patients and tissue microarrays made for IHC assessment. Factors assessed for the effect on FFS of first-line therapy were: liver metastases; ALP; grade; mucoid status; age; and IHC for dUTPase and TS. Log-rank univariate analyses and Cox Model multivariable analysis was performed. Results: Univariate analysis of the validation set failed to confirm evidence of the previously observed association between high TS expression and FFS (p=0.2); however high dUTPase IHC (p=0.01), ALP (p<0.0001) and grade (p=0.001) showed significant associations. Table 1 illustrates the results of univariate and multivariable analysis of the combined test and validation sets. In the Cox Model, high TS IHC expression, tumor grade and baseline serum ALP were highly significant predictors of reduced FFS. Conclusions: We failed to confirm a significant association between high TS expression and reduced FFS in an independent validation set. However, in an exploratory analysis of the combined validation and test sets (n>1000), TS IHC expression remained a highly significant predictor of FFS. Overall, our results cannot be taken to demonstrate a powerful and clinically useful influence of TS on treatment efficacy, but are consistent with a moderate effect.

[Table: see text]

No significant financial relationships to disclose.

Radiotherapy for Ductal Carcinoma In Situ

AIMS

The introduction of breast screening mammography has led to an increase in the diagnosis of ductal carcinoma in situ (DCIS). Mastectomy gives high rates of local control. However, most cases are suitable for local excision. The aim of this article is to review the role of radiotherapy in the treatment of DCIS after breast conserving surgery.

MATERIAL AND METHODS

A review of the literature relating to radiotherapy and DCIS RESULTS: The published trials show that adjuvant radiotherapy after breast conserving surgery halves the ipsilateral recurrence rates of DCIS and invasive cancer. No subgroups have been reliably identified that do not benefit from adjuvant radiotherapy. Risk factors for recurrence are discussed.

DISCUSSION

All patients with DCIS have potential benefit to gain from adjuvant radiotherapy. However, radiotherapy also has adverse effects and represents over-treatment from many women. Support should be given to current trials which are assessing endocrine treatment of DCIS, and whether radiotherapy can reasonably be omitted in lower risk disease.

Cancer knowledge of the general public in the United Kingdom: survey in a primary care setting and review of the literature

The likelihood of cure from cancer is usually dependent on the stage of disease at diagnosis. Some patients attend their general practitioner with a long preceding history of cancer symptoms. This may be due in part to a lack of recognition of the seriousness of the symptoms. We have conducted a survey of 406 adult patients in a two-centre primary care practice to determine their awareness of risk factors, presenting symptoms, treatments and support services for cancer. The two health centres are located in areas covering different socio-economic groups--one located in an affluent residential area, and the other a deprived inner-city population. Significant deficiencies were identified in the cancer knowledge of respondents. Personal or family history of cancer, younger age and female sex were associated with improved cancer awareness. A review is also presented of the previous published literature on the cancer knowledge of the general public in the U.K. The results suggest that overall the public knowledge of cancer is poor and greater attempts should be made to raise awareness.

Morbidity of tamoxifen–perceptions of patients and healthcare professionals

There is little published data comparing patients' and doctors' perceptions of tamoxifen-related morbidity and toxicity, in particular in terms of side-effects which are not medically serious but which disrupt quality of life. We undertook a questionnaire-based study of 210 randomly selected, disease-free pre- and post-menopausal breast cancer patients to assess perceived morbidity whilst taking tamoxifen. We also questioned 143 healthcare professionals, including nurses, GPs and oncologists, on their opinions of tamoxifen-related side-effects. This study suggests that patients experience significant morbidity while taking adjuvant tamoxifen but will tolerate this for the sake of anticipated benefits. Healthcare professionals particularly hospital-based doctors and specialist nurses tend to overestimate the prevalence and severity of tamoxifen-associated symptoms.

Open access follow-up for lung cancer: patient and staff satisfaction

The majority of patients with lung cancer have incurable disease from presentation and a survival measured in months. Treatments offered to these patients are aimed at the palliation of symptoms with either radiotherapy or chemotherapy, or with supportive measures. It has been traditional to offer regular outpatient follow-up after initial palliative treatment. Further treatment options, which may be limited, are usually reserved for the recurrence of troublesome symptoms. A pilot 'open access' lung cancer clinic has been set up. Rather than have regular follow-up at the hospital, patients who have completed initial palliative treatments are discharged to the community with follow-up by their general practitioner and Macmillan nurse. Review at the open access clinic can be arranged at short notice if requested by the patient, carers, general practitioner or Macmillan nurse. The outcomes and level of satisfaction of patients, their relatives and staff to this method of follow-up were found to be positive. Open access follow-up may be useful for many patients after the completion of initial palliative treatment.

Optimum anthracycline-based chemotherapy for early breast cancer

Adjuvant chemotherapy improves the overall survival of women treated after surgery for early breast cancer. Several trials have suggested that anthracycline-containing regimens are more effective than those that do not contain anthracyclines. A modest overall benefit has also been confirmed by the Early Breast Cancer Trialists' Collaborative Group overview. Newer agents, such as the taxanes, are now being tested in the adjuvant setting in randomised trials. The control group of such studies should receive the optimum standard treatment. There are several anthracycline-based regimens in common use, varying in terms of the type of anthracycline used, the dose, and drug scheduling. We review the available evidence and consider whether the optimum anthracycline-containing chemotherapy schedule has now been identified.

Thalidomide in the treatment of cancer

Thalidomide caused severe malformations in babies born to mothers taking the drug for morning sickness in the late 1950s and early 1960s. It is now known that these teratogenic effects are due to potent anti-angiogenic and immunomodulatory actions. These properties have lead to the testing of thalidomide in a number of infective, inflammatory and malignant conditions. Promising activity has been reported in myeloma, AIDS-related Kaposi's sarcoma, renal cell carcinoma and glioblastoma multiforme. A review is presented of the history of thalidomide and its recent development with an emphasis on applications in malignant disease.