HIF expression and Max-SUV-18F-FDG-PET in non-small cell lung cancer (NSCLC) patients

e22010

Background: Tumor hipoxia induces the up-regulation of several genes via the hipoxia-inducible transcription factors (HIF) 1 and 2. HIF-2 alpha (HIF-2 α) and HIF-1 alpha (HIF-1α) are associated with the prognosis of operable NSCLC patients. We studied the immunohistochemical expression of HIF-1α and HIF-2 α in patients with NSCLC and the possible correlation with the maximum standardised uptake value (max SUV) of 18F-FDG as well as other biological parameters. Methods: We used a Tissue Arrayer device (Beecher Instruments. WI) to construct a TMA block, according to conventional protocols for the study of immunohistochemical expression of HIF-1α, HIF-2 α, EGFR, bcl-2, MIB1, p16, p63 and cyclins A, B1, D1 and D3. Sections were scored as positive if >10% of cells stained positively. Staining patterns were correlated to clinical variables. Results: HIF- 1α expression was observed in 84/96 patients (34/39 adenocarcinomas and 50/57 squamous cell carcinomas), however it did not correlate with clinical stage (I-II: 41/45 vs III-IV: 44/51). HIF-1α correlated positively with HIF-2 α (p:0,001) and EGFR (p:<0,001) expressions. The maxSUV values of 18F-FDG-PET were higher (p:0,039) in HIF-1α -positive (17,1±8,6) than in negative tumors (11,8±4,4). HIF-2 α expression was observed in 60/103 cases (27/42 adenocarcinomas and 33/61 squamous cell carcinomas) and it did not correlate with clinical stage ((I-II: 28/45 vs III-IV: 32/57). HIF-2 α correlated positively with HIF-1α (p:0,001), MIB1 (p:0,045) and EGFR (p:0,091) expressions. After multivariate analysis, only the clinical stage (RR: 2,2) was a prognostic factor. Conclusions: 1) HIF-1α and HIF-2 α expressions are frequent in patients with NSCLCs and it did not correlate with clinical stage; 2) maxSUVs FDG-PET values were higher in HIF1alpha positive than in HIF-1α negative patients; 3) HIF-1α was correlated with EGFR expression, while HIF-2 α was correlated with MIB1 expression.

No significant financial relationships to disclose.

[The immunohistochemical expression of cyclin B1 is associated with higher SUV in 18F-FDG-PET in non-small cell lung cancer patients. Initial results]

AIM

to study the expression of cyclin B1 and its possible relationship with the maximum SUV in FDG-PET and MIB1 expression in patients with NSCLC.

MATERIALS AND METHODS

49 patients (15 adenocarcinomas, 27 squamous cell carcinomas and 7 bronchoalveolar carcinomas) were included in this study; the immunohistochemical expression of cyclin B1 was determined using the tissue-array technique. Each PET was performed 60 minutes after the i.v. administration of 350-518 MBq of FDG on an Advance system (GE) in 2D acquisition mode.

RESULTS

cyclin B1 expression was detected in 40 out of 45 cases. The SUV values were higher (p=0.04) in the cyclin B1+ cases than in the negative cases (16.4+/-8.1 vs 10.9+/-6.2). Cyclin B1 expression and SUV values were not correlated with the clinical stage. The expression of cyclin B1+ correlated positively (p<0.0001) with that of MIB1. After univariate analysis, only the cellular proliferation was a prognostic factor (p=0.037).

CONCLUSIONS

our results suggest that there is a direct correlation between cyclin B1 expression and max-SUV values in the PET of NSCLC patients. When the association of cyclin B1 with positive MIB1 is also considered, our results support the role of cell proliferation in FDG uptake by the tumour.

[The immunohistochemical expression of cyclooxygenase 2 is inversely associated with (18)F-FDG-PET SUV values in non-small-cell lung cancers. Initial results]

OBJECTIVE

To study the expression of COX-2 and its possible relationship with the maximum standardized uptake value (SUV) in FDG-PET, and EGFR, p16 and MIB1 expression in patients with NSCLC.

MATERIAL AND METHOD

45 patients (12 adenocarcinomas and 33 squamous cell carcinomas) were included in this study; the immunohistochemical expression of COX-2, MIB-1, p16 and EGFR was determined using tissue-array. Each PET was performed 60 minutes after the i.v. administration of 350-518 MBq of FDG on an Advance system (GE) in 2D acquisition mode.

RESULTS

COX-2 expression was detected in 35 out of 45 cases, and was very significant (> ++) in 12 of them. SUV values were lower in the COX-2 > ++ cases that in the remaining cases (13.4 +/- 1.2 vs. 12.9 vs. 17.1 +/- 1.5; p = 0.059). COX-2 > ++ expression and maxSUV values were not correlated with the clinical stage. The expression of COX-2 > ++ was correlated positively with p16 (r = 0.36; p = 0.014) and negatively with MIB1 (r = -0.32; p = 0.041) expression, whereas the SUV was correlated positively with EGFR (r = 0.44; p = 0.004) and negatively with p16 (r = -0.29; p = 0.041) expression.

CONCLUSIONS

Our results suggest that: a) the expression of COX-2 > ++ is often found in this kind of lung cancer and is not associated with the clinical stage; b) the maxSUVs were not related to the stage and were lower in COX-2 > ++ tumours than in the other cases; and c) the different behaviour of both parameters can be explained by their correlation with cell proliferation (MIB1), EGFR and p16 expression.

Evaluating new candidate SNPs as low penetrance risk factors in sporadic breast cancer: a two-stage Spanish case-control study

OBJECTIVES

A polygenic model has been proposed in order to explain the genetic susceptibility to sporadic breast cancer. According to this model, common population variants would be responsible for low to modest effects on the risk of developing the disease. We have carried out a high-throughput SNP genotyping project in order to shed some light on the complex genetic aetiology of non-familial breast cancer.

METHODS

Ninety-one genes have been selected because of their implications in several candidate cell pathways for breast cancer. A total of 640 SNPs in these genes were genotyped in a series of 450 consecutive cases and 448 controls from mainland Spain. Promising SNPs were then studied in an independent series of 294 cases and 299 controls from the Canary Islands.

RESULTS

In the first case-control series we identified 25 SNPs with P-values below 0.05 (under a 1 df Chi-square test), five of them with P-values below 0.01 (best=0.0008). In the stage 2 Canary Islands series, odd ratios (OR) for two SNPs in HUS1 were in a consistent direction.

CONCLUSIONS

SNPs located at the gene HUS1 are good candidates for further investigation in independent association studies and functional assays.

[18FDG-PET in patients with in situ breast carcinomas. A cause of false negative results]

BACKGROUND AND OBJECTIVE

To study the behaviour of 18F-FDG-PET in patients with in situ breast carcinomas.

PATIENTS AND METHOD

The study group included 19 women with a tumor size between 0.8 and 2.2 cm. An uptake in breast with a SUV > 1.9 was considered as positive.

RESULTS

18F-FDG-PET was positive in 8 patients (SUV; range 0.6-2.8; 1.64 [0.59]) and only when the tumor size was higher than 1 cm. Likewise, only in the PET-positive tumors, an inverse (r = -0.637) and positive (p < 0.05) correlation between SUV and weight of patients was observed. When we compared the results with those obtained in 28 patients having infiltrating ductal carcinomas of the breast, we observed that the 18F-FDG-PET was positive only in tumors > 1 cm also, but the percentages of positives (89%) were higher than those obtained in in-situ carcinoma, regardless of tumor size.

CONCLUSIONS

The percentage of positive results of 18F-FDG-PET in in-situ breast carcinomas and the SUV are lower than those observed in infiltrating ductal carcinomas, regardless of tumor size. Those carcinomas can be a source of false negative results with such imaging technique.

Reduced clinicopathological influence of hormone-dependence on breast carcinomas in women older than 70 years

In order to evaluate the influence of hormone dependence on the features of infiltrating ductal carcinoma of the breast we have assayed the cytosolic levels of estrogen receptor (ER), progesterone receptor (PR), pS2 and cathepsin D in 53 women aged over 70 years and in 95 women aged between 55 and 70 years. Tumor size, axillary involvement, distant metastasis, histological grade, ploidy and S-phase were taken into account. Carcinomas of women aged over 70 did not show higher concentrations or higher positive results for ER and PR than those of women in the 55-70-year age group. In older patients, negativity for ER was associated only with higher S-phase fraction, while negativity for PR was not associated with any of the parameters analyzed. In the younger subgroup, negativity for ER was associated with larger tumor size, higher S-phase fraction, lymph node involvement, histological grade 3 and lower pS2 values. Negativity for PR was associated with the same parameters, as well as with a higher frequency of recurrence. Our results suggest a reduced influence of hormone dependence on the clinicopathological features of breast carcinomas in patients older than 70 years compared with women aged between 55 and 70 years.

Reduced Clinicopathological Influence of Hormone-Dependence on Breast Carcinomas in Women Older than 70 Years

In order to evaluate the influence of hormone dependence on the features of infiltrating ductal carcinoma of the breast we have assayed the cytosolic levels of estrogen receptor (ER), progesterone receptor (PR), pS2 and cathepsin D in 53 women aged over 70 years and in 95 women aged between 55 and 70 years. Tumor size, axillary involvement, distant metastasis, histological grade, ploidy and S-phase were taken into account. Carcinomas of women aged over 70 did not show higher concentrations or higher positive results for ER and PR than those of women in the 55–70-year age group. In older patients, negativity for ER was associated only with higher S-phase fraction, while negativity for PR was not associated with any of the parameters analyzed. In the younger subgroup, negativity for ER was associated with larger tumor size, higher S-phase fraction, lymph node involvement, histological grade 3 and lower pS2 values. Negativity for PR was associated with the same parameters, as well as with a higher frequency of recurrence. Our results suggest a reduced influence of hormone dependence on the clinicopathological features of breast carcinomas in patients older than 70 years compared with women aged between 55 and 70 years.

[Preoperative CA15.3 serum levels and cellular proliferation in patients having infiltrating ductal carcinomas of the breast]

OBJECTIVE

To study the possible correlations between the preoperative CA15.3 serum levels and the cellular proliferation, measured by S-phase (SP), in patients having infiltrating ductal carcinomas (IDC) of the breast

MATERIAL AND METHODS

The study group included 79 patients with an age ranged between 39 and 86 yrs (64,8 +/- 11,8). Ploidy and S-phase were measured by cytometry (Fascam. Beckton Dikinson. USA) in fresh samples

RESULTS

Using as cut-off for SP the value of 7 %, which represents the median obtained previously in 321 patients with IDC (r: 0,8-51,2; 9,3 +/- 7,9; percentiles 25 y 75; 4,3 y 11,8 %), we can observed that the antigenic levels were higher (p:0,015) in the tumors with low SP. These same behavior was noted when 30U/ml was used as cut-off for CA15.3. Likewise, the levels of the tumor marker increased significantly (p:0,007) when the SP moved from < 4,3 % to 7,1 %, to decrease later (p:0,010) when the SP value was comprised between 7,11 % and 11,8 %. The same behavior of this tumor marker in relation to the SP was noted in tumors without axillary involvement tumors, as well as in aneuploid carcinomas.

CONCLUSION

a) Release of CA15.3 happens when SP increases to rise the 7,1 % value, to decrease later although that goes on increasing, and b) The same behaviour of this marker with the S-phase was observed in tumors without axillary involvement, as well as in aneuploid carcinomas.

[Evolution in 18F-FDG-PET of a case of Hodgkin disease, nodular sclerosis variety, after treatment and autotrasplant]

Positron Emission Tomography (PET) has become a very useful tool for monitoring Hodgkin's disease patients in the last years. When there is suspicion of disease persistence after treatment, this technique makes it possible to evaluate treatment activity of the residual lesions observed in the CT scan. Furthermore, due to the whole body study, new tumor sites, which very often change the therapeutic option, can be detected. We must take into account, however, that 18F-FDG is a very sensitive but not very specific tumor marker, since some inflammatory or infectious conditions may be associated to significant radiopharmaceutical uptakes. Thus, in order to increase specificity it is mandatory to correlate the PET information with the rest of the conventional imaging and clinical data and evolution of the patient. We present the case of a woman with Hodgkin's disease in which 18F-FDG PET was included in the follow-up. Both conditions, tumor and infection, were present in different times of the course. The integration of all the x-ray, clinical, laboratory and metabolic information allowed for a better and correct management of this patient.

Valor actual de la tomografía por emisión de positrones durante el seguimiento del cáncer de próstata

Positron emission tomography (PET) is a non-invasive nuclear medicine technology which uses radiotracers and cameras slightly different from the ones used in other nuclear medicine tests. Most current indications are for oncological diseases; in nephrology-urology its use has been reduced because of the characteristics of the most commonly used radiotracer, 18F-fluor deoxiglucose (18F-FDG, a glucose analogue), which is excreted by the kidney, limiting the interpretation of the study in urologic malignancies. Currently, 18F-choline is a promising radiotracer for both staging and restaging, especially if hybrid PET/CT scan devices are used. New radiotracers will be needed in the evolution of PET to obtain information about more specific aspects of prostate carcinoma that will modify therapy and follow-up.

[Preoperative serum CA15.3 and CEA levels and clinical-biological parameters in breast tumors]

OBJECTIVE

To study the possible associations between preoperative serum CEA and CA15.3 levels and different clinical-biological parameters of infiltrating ductal carcinomas of the breast (IDC).

PATIENTS AND METHOD

Preoperative serum CA15.3 and CEA levels were determined in 255 and 224 females, respectively, having IDC. We assayed the cytosolic levels of estrogen receptor, pS2, cathepsin D and hyaluronic acid, as well as the levels of epidermal growth factor receptor in cell surfaces. Tumor size, axillary involvement (N), distant metastasis (M), histological grade (HG) and cellular S-phase (SP) were taken into account.

RESULTS

22 IDC were positive for CA15.3 (> 40 U/ml) and they had greater global tumor size (p < 0.001), > 2 cm (p: 0.005) and distant metastasis (p < 0.001). 19 IDC were positive for CEA (> 4 ng/ml) and they had greater global tumor size (p < 0.001), > 2 cm (p < 0.001), > 5 cm (p: 0.052) and global S-phase values (p: 0.062), and were more frequently N + (p: 0.045), > 3N + (p: 0.001) and > 10N + (p < 0.001), M + (p: 0.004), HG3 (p: 0.091) and SP > 7 % (p: 0.006).

CONCLUSIONS

Our results led us to the following: In patients having IDC of the breast, preoperative serum CA15.3 levels are associated with greater tumor size and distant metastasis, while pre-treatment CEA serum levels are associated moreover with axillary involvement; we have not observed any correlation between serum levels of both antigens and the hormonal status of the tumor; these results had physiopathological interest but reduced clinical value in pretreatment breast carcinomas due to their low sensitivity of both markers. However, they are useful in the follow-up of the patients when assessing serum concentrations of both markers, since they contribute to knowing the patients' clinical status better.

La expresión del receptor del factor de crecimiento epidérmico (EGFR) en carcinomas mamarios hormonoindependientes

OBJECTIVE

To determine the expression of epidermal growth factor receptor (EGFR) in ER-negative and Pg-R negative infiltrating ductal carcinomas of the breast (IDC) and to analyze the possible relationship between the EGFR positivity and some clinico-biological parameters of tumors.

MATERIAL AND METHODS

EGFR was measured by a single point radioligand assay in the cell surfaces of 115 ER-negative and Pg-R-negative (< 10 fmol/mg prot.) IDC. We measured also the cytosolic concentrations of pS2, cathepsin D, tissue-type plasminogen activator (t-PA) and hyaluronic acid (AH), as well as the levels of AH in cell surfaces. Tumor size, axillary involvement, distant metastasis, histological grading, ploidy and S-phase (SP) were taken account.

RESULTS

Using as cut-off for EGFR a value of 5 fmol/mg prot., we can observed that IDCs -EGFR + had greater global values of S-phase (p: 0.005) and were more frequently metastastatic (p: 0.004), SP > 7 % (p < 0.001) and SP > 14 % (p: 0.077); likewise, they were lower frequently pS2-positive (p < 0.01) and t-PA-positive (p < 0.01). During the follow up time (median 85 months), the number of recurrences was higher in EGFR-positive than in EGFR- negative tumors (14/41 frente a 1/29; p: 0.002), but there was not differences in the number of deaths by the tumor.

CONCLUSIONS

1) The EGFR-positivity in ER-negative and PgR-negative IDCs is associated with distant metastasis, greater cellular proliferation (SP), lower positivity for pS2 and t-PA and greater number of recurrences. 2) Using 10 fmol/mg prot. as cut-off, we observed the same findings, except the change in cellular proliferation. 3) Our findings support the possible use of EGFR as a prognostic parameter in those breast carcinomas.

Estrogen and progesterone receptor gene polymorphisms and sporadic breast cancer risk: A Spanish case-control study

Estrogens, and to a lesser extent progesterones, influence the proliferation, differentiation and physiology of breast tissue as well as the development and progression of breast cancer. Genetic variants in the steroid hormone receptor genes ESR1 and PGR (belonging to the nuclear receptor superfamily) could therefore modify sporadic breast cancer susceptibility. Two studies have shown a protective effect associated with variants in ESR1 in 2 distinct populations. We studied 4 single nucleotide polymorphisms (SNPs) in ESR1 and 4 in PGR in 550 consecutive and unrelated sporadic Spanish breast cancer patients and 564 healthy Spanish controls. We observed a dominant protective effect for the S10S variant in ESR1, with an estimated odds ratio (OR) of 0.75 (95% CI = 0.58-0.97; p = 0.03) although functional studies did not show changes in the RNA stability. A small subset of individuals carried a haplotype combination that corroborates this protection. No other SNP considered in either gene was found to be associated with sporadic breast cancer. Our results obtained in a European population confirm the protective role of the S10S variant in ESR1, previously reported in an Asian and a European-American population.

[Asymmetric pulmonary perfusion causing unilateral pulmonary edema as a complication of acute myocardial infarction]

Acute unilateral pulmonary edema is an unusual clinical condition occasionally associated with severe mitral valve insufficiency. We describe a patient diagnosed as having unilateral pulmonary edema after an acute anterior myocardial infarction. Echocardiograms performed in the acute phase ruled out mitral insufficiency. A perfusion lung scan showed left-sided pulmonary hypoperfusion. The diagnosis of acquired hypoplasia of the left pulmonary artery tree was made by chest computed tomography. The pathogenesis and differential diagnosis are discussed.

[Cytosolic pS2 levels and cellular proliferation in ER-positive and PgR-positive infiltrating ductal carcinomas of the breast]

OBJECTIVE

The trefoil factor 1 (TFF1/pS2) is an estrogen-induced molecule in breast tumours. We wanted to study its expression in ER+ and PgR+ infiltrating ductal carcinomas of the breast (IDCs), and to correlate it with other clinical-biological parameters and the outcome.

MATERIAL AND METHODS

Cytosolic pS2 levels were measured using an IRMA (CIS. Biointernational. France) in 170 tumors. Likewise we determined the cytosolic levels of cathepsin D and tissue-type plasminogen activator (t-PA), as well as the concentrations of the epidermal growth factor receptor (EGFR), erbB2 oncoprotein, CD44v5 and CD44v6 on cell surfaces. Also the tumour size, histological grade (HG), axillary lymph node involvement, distant metastasis, ploidy, DNA index and of cellular synthesis phase (SP) was taken in account.

RESULTS

The pS2-positive (> 5 ng/mg prot.) tumours showed higher concentrations of cathepsin D (p: 0.0043) and t-PA (p: 0.0089) than the pS2-negative ones. Likewise, they were less frequently HG3 (p: 0.0231), SP > 7 % (p: 0.0005) and SP > 14% (p:0.0014). During the follow-up time (r: 1-147; 50,1+/-31,7; median 37 months) the pS2-positive tumors showed a less number of recurrences (5/101 vs 6/69; p: 0.059) but not of deaths by the tumor (1/101 vs 2/69).

CONCLUSIONS

These results support an inverse relationship between pS2 positivity and cellular proliferation in IDCs and suggest a new role of this protein (different of the hormone dependence) in the biology of these breast carcinomas, while further studies will be required to establish the impact of this finding on their outcome.

[CA125 cytosolic levels in lung adenocarcinomas. New biological aspects]

INTRODUCTION

CA125 is a useful serum tumor marker in patients with non-mucinous ovarian cancer, but there may be high serum levels in other malignant tumors, among them the non-small cell lung cancers. We decided to study the cytosolic levels of CA125 in lung adenocarcinomas and compare them with pS2, CD44s, CD44v5 and CD44v6, all of them with biological interest in this subtype of lung carcinomas.

SUBJECTS AND METHODS

The study group included 55 patients (33 males) having lung adenocarcinomas. CA125 and cytostolic pS2 were measured by both IRMAS methods (CIS. Biointernational. France). The concentrations of CD44 standard (CD44s), CD44v5 and CD44v6 on cell surfaces were dosed by EIAS (Bender Diagnostics. Austria). Clinical stage, ploidy and S-phase cellular fraction were also taken into account.

RESULTS

In the 55 lung adenocarcinomas, cytosolic CA125 levels ranged between 1 and 225 U/mg prot. (median 80.5) and were higher (p:0.002) than those observed in 16 normal lung tissues from the same patients (r: 1-32.5; median 6.7 U/mg prot.). When the 25th (7.2 U/mg prot.) and 75th (320 U/mg prot.) percentiles were used as clinical cut-offs, we found that the cases with high antigenic levels showed a greater positivity for CD44v6 (p:0.002) and a reduced positivity for CD44 standard (p:0.053). Likewise, they showed a tendency towards being pS2 + (p:0.09) more frequently.

CONCLUSIONS

Our results lead us to draw the following conclusions: 1) Cytosolic CA125 levels in lung adenocarcinomas were higher than those observed in normal tissues from the same patients. 2) Lung adenocarcinomas with high cytosolic CA125 concentrations had a greater positivity for CD44v6, a reduced positivity for CD44s and were more frequently pS2 +. These associations support the usefulness of the cytosolic CA125 levels as an indicator of poor outcome in this subtype of lung carcinomas.

[Hepatic abscess demonstrated by 67Ga-citrate scintigraphy within a diagnosis of fever of unknown origin]

We report a case of a 63 year old man who was seen in the hospital because of fever having a possible infectious or oncological origin. A 67Ga scintigraphy was performed and showed high pathological accumulation in the hepatic dome. The patient was re-evaluated and studied with other diagnostic tests including a CT scan, coinciding with the findings in the 67Ga-citrate scintigraphy. A correct final diagnosis of liver abscess was made.

Dental diseases and radionuclide imaging of the jaws

The aim of this study was to compare the results of radionuclide bone scans of the jaws with data obtained at the nuclear medicine department from a brief and feasible dental history, taking special account of cases with a positive scan and no recent dental events. Ninety-eight patients undergoing radionuclide bone scan as part of their diagnosis in non-dental, oncological and non-oncological diseases were imaged with 99mTc-labelled oxidronate. Superior and inferior halves of the mandible and maxilla (392 quadrants) were regarded as normal or having an abnormally high uptake. A recent (1 year) dental history was also obtained through a brief questionnaire and data were referred to each quadrant of the jaws. The association between the bone scan and dental disease was assessed by means of the chi-squared test. The overall results of scintigraphy and history coincided in 66 patients (46 with abnormal and 20 with normal findings; P = 0.002). Twenty-five patients had a positive scintigram without any known dental disorder. Results of scintigraphy and history coincided in 254 quadrants (78 with abnormal and 176 with normal findings; P < 0.001). Eighty-three quadrants had hot spots in the scintigram without any known dental lesion. It can be concluded that abnormal jaw scintigrams are frequent in patients without known dental disease, and this may indicate silent osteoblastic activity. These observations should be reported to the dentist for several reasons. First, they may reveal asymptomatic dental lesions. Second, the use of oral prostheses and implants is increasing and they require the support of healthy alveolar bone.

[Axillary lymph node involvement in hormone-independent breast carcinomas]

BACKGROUND AND OBJECTIVE

We decided to study the axillary lymph node invasion (N) in hormone-independent breast cancer.

PATIENTS AND METHOD

The study group included 77 ER and 47 ER/PgR breast carcinomas. Both ER and PgR were determined using EIAS from Abbott (USA).

RESULTS

In ER tumors, one the most important finding was the high concentration (p = 0.001) and percentage of positives ( > 50 pmol/mg prot.; 24/41 vs 7/36; p < 0.01) of cathepsin D observed in N+ vs N- tumors. In ER/PgR negative tumors, lymph node involvement was associated with a same behavior of this proteinase (p = 0.021; 17/31 vs 2/16; p = 0.006) exclusively.

CONCLUSIONS

Our results point to a possible usefulness of cathepsin D in this type of carcinomas.

The variant E233G of the RAD51D gene could be a low-penetrance allele in high-risk breast cancer families without BRCA1/2 mutations

Six SNPs have been detected in the DNA repair genes RAD51C and RAD51D, not previously characterized. The novel variant E233G in RAD51D is more highly represented in high-risk, site-specific, familial breast cancer cases that are not associated with the BRCA1/2 genes, with a frequency of 5.74% (n = 174) compared to a control population (n = 567) and another subset of breast cancer patients (n = 765) with a prevalence of around 2% only (comparison to controls, OR = 2.6, 95% CI 1.12-6.03; p < 0.021). We found that the immunohistochemical profile detected in available tumors from these patients differs slightly from those described in non-BRCA1/2 tumors. Finally, the structural prediction of the putative functional consequence of this change indicates that it can diminish protein stability and structure. This suggests a role for E233G as a low-penetrance susceptibility gene in the specific subgroup of high-risk familial breast cancer cases that are not related to BRCA1/2.