Abstract P2-08-01: PIK3CA mutations associate with decreased Ki67 in early stage breast cancer (BC) and better outcomes in patients even among those with low Ki67 tumors

Background: In studies of over 450 BC patients (pts) with > 10 years follow-up, pts with PIK3CA-mutated primary tumors had improved clinical outcome (Kalinsky et al 2009, Cizkova et al 2012). PIK3CA mutations associated with favorable clinicopathologic features: lower grade, smaller size, lymph node negativity (−), ER positivity (+), HER2−. In BC, several studies have suggested that PIK3CA mutations do not associate with PI3K/mTOR pathway activation (Loi et al 2010, Stemke-Hale et al 2008). To gain additional insight into the favorable biology imparted by a PIK3CA mutation in early stage BC and to identify predictive biomarkers, we performed immunohistochemistry (IHC) on tissue microarrays (TMA) constructed from 590 primary BCs.

Methods: TMAs derived from FFPE tumors previously genotyped for PIK3CA mutations (rate of 32.5%, 192/590) were stained for ER, HER2 and AR (Kalinsky et al 2009). Here, we performed additional stains for MIB1 (Ki67 proliferation index, Ki67), p53 and markers of PI3K pathway activation (pS6, PTEN). Slides were scanned with Aperio ScanScope XT and segmented using TMALab (Aperio). Images were analyzed with the Aperio algorithm based on staining pattern (nuclear, cytoplasmic, membrane) and scored for % + and intensity. Manual review was performed for tumors with less than 3 cores or discordant results. PTEN was scored manually: 0 (no tumor staining, PTEN loss), 1 (tumor < stroma), or 2 (tumor ≥ stroma). P values were based on the log-rank test for comparison of Kaplan-Meier curves for disease free survival (DFS), Chi-square test for categorical variables and t-test for continuous variables.

Results: On average, 66 cases (11%) were non-informative for each IHC stain, due to missing cores or insufficient tumor cells. In a binary analysis of Ki67 using a cutoff of ≥10% + cells, PIK3CA mutated tumors demonstrated significantly lower proliferation index with only 9.4% of tumors (16/170) having high Ki67 as compared to 23.6% of wild-type PIK3CA tumors (82/347) (P = .001). Ki67 was also highly associated with PIK3CA genotype when analyzed with a cutoff of ≥13.25% + cells or as a continuous variable. Importantly, DFS was significantly different when analyzed by PIK3CA genotype and Ki67 (P = .01). Among pts with low Ki67 tumors (n = 419), PIK3CA mutation associated with longer DFS (10yr 79%, CI 69–85) as compared to wild-type PIK3CA (10yr 71%, CI 64–77). When PI3K pathway interactions were analyzed, PTEN loss associated with wild-type PIK3CA (P<.001), although PTEN loss occurred with mutated PIK3CA in 11 hormone receptor (HR)+ tumors. In analysis of pS6 with a binary cutoff of ≥20% + cells, high pS6 associated with HER2+ (P<.001), HR- (P<.001) and high tumor grade (P = 0.003), but did not associate with PIK3CA genotype (P = .13). PIK3CA mutation was associated with lower pS6 when pS6 % + cells was analyzed as a continuous variable (P = .01).

Conclusions: PIK3CA mutation associates with lower Ki67 in early stage BC. Even among pts with low Ki67 tumors, PIK3CA mutation associates with improved clinical oucome. pS6 is not increased in PIK3CA-mutated tumors which likely indicates that mTORC1 signaling is not activated as a result of PIK3CA mutation in early stage ER+ BC.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P2-08-01.

Use of multiplex mutation genotyping to identify novel and protective mutations in breast cancer

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Background: We recently analyzed 590 primary invasive breast tumors for PIK3CA mutations by multiplex massARRAY genotyping. We identified a 32.5% PIK3CA mutation rate (manuscript submitted). Associations between PIK3CA mutation status and favorable pathology, such as lower grade tumors, lymph node negativity and hormone receptor (HR) positivity, were observed. Multiplex analysis allows the rapid assessment of mutations not commonly described in breast cancer. To identify activated pathways that may serve as predictive biomarkers, tissue microarrays (TMA) underwent immunohistochemical (IHC) analysis. Methods: 590 archival formalin-fixed paraffin embedded (FFPE) tumors > 1 cm were used to ensure adequate tissue procurement for mutation detection and TMA construction. MassARRAY (Sequenom) genotyping was performed on native DNA to identify PIK3CA, RAS, RET, and other known mutations. IHC staining of the TMAs included assessment of steroid nuclear receptors, HER2 expression, Akt pathway activation (including pAKT, p70S6K, eIF4E), and PTEN. Stained TMAs underwent digital quantitative image analysis and scoring (Aperio, Vista, CA). The Kaplan-Meier method and Cox models were used in univariate and multivariate analysis for associations of mutation status and clinicopathologic features on overall survival (OS) and breast cancer-specific survival (BCSS). Results: Compared to wild-type, PIK3CA mutated tumors (median f/u: 12.8 years) demonstrate a significant improvement in OS (p=0.03) and BCSS (p=0.004). For patients with any PIK3CA mutation, the improvement in BCSS is maintained in HR positive and ER negative subgroups. In addition to PIK3CA mutations, RAS and RET mutations are identified in a small proportion of breast tumors. Additional analysis to evaluate the association of mutation status and biomarker data derived from the TMA analysis will be performed for meeting presentation. Conclusions: We have recently defined the positive prognostic significance of PIK3CA mutations in breast cancer. RAS mutations are confirmed to occur rarely in breast cancer. The finding of RET mutations in breast cancer is novel. Future tumor biomarker identification directed towards predictive measurement will assist in tailoring therapy to appropriate patient populations.

No significant financial relationships to disclose.

Treatment of selected neuromuscular patients with posterior instrumentation and arthrodesis ending with lumbar pedicle screw anchorage

STUDY DESIGN

This is a retrospective analysis of 23 patients with severe neuromuscular spinal deformity treated with posterior instrumentation and fusion ending in the lumbar spine.

OBJECTIVES

The purposes of this study were to determine the safety and efficacy of stopping posterior instrumentation constructs in the lumbar spine with pedicle screw anchorage.

SUMMARY OF BACKGROUND DATA

There are sparse data in the peer-reviewed literature regarding indications and outcomes in patients with neuromuscular disorders for instrumented fusion ended short of the pelvis with transpedicular fixation.

METHODS

The average age of patients at surgery was 18.4 years (range, 10-61 years). Additional anterior discectomy and fusion were performed in four patients with large, stiff curves. No patient received anterior instrumentation. Criteria for exclusion of the pelvis from the fusion were less than 15 degrees of pelvic obliquity as a result of a compensatory curve below the major curve(s), the absence of problematic lower extremity contractures, and, often, the potential for ambulation. Process and clinical outcomes and complications were analyzed.

RESULTS

Radiographic follow-up was available in 21 patients at an average of 62 months (range, 24-110 months) after surgery. Their average Cobb angle was 71 degrees before surgery, 25 degrees after surgery (64% correction), and 32 degrees at follow-up (54% correction). Their average spinal-pelvic obliquity was 6 degrees before surgery, 5 degrees after surgery, and 6 degrees at follow-up. The average lower instrumented vertebra was lumbar 3.7. Clinical follow-up was available for all 23 patients for an average of 61 months (range, 24-110 months). There were no perioperative deaths, deep wound infections, pseudarthroses, or instrument failures. Outcomes based on responses to questionnaires completed by patient, parent, or caregiver were highly satisfactory in 20 patients (87%), satisfactory in 2 patients (9%) and neither satisfactory nor unsatisfactory in 1 patient (4%).

CONCLUSION

Posterior instrumentation and arthrodesis using lumbar lower instrumented vertebra pedicle screw anchorage can be performed safely and effectively, in selected patients patients with scoliosis and minimal pelvic obliquity.

Reoperation after primary posterior instrumentation and fusion for idiopathic scoliosis. Toward defining late operative site pain of unknown cause

STUDY DESIGN

Retrospective case series.

OBJECTIVES

To determine the frequency and categorize the indications for reoperation in three implant systems (Harrington, Cotrel-Dubousset [C-D], and Isola). To define late operative site pain (LOSP) of no apparent cause as an indication for implant removal and determine the success of implant removal in relieving LOSP.

SUMMARY OF BACKGROUND DATA

Late operative site pain of no apparent cause has been discussed briefly in the literature but has not been investigated as a major indication for implant removal.

METHODS

One hundred eighty-two of 190 consecutive patients with idiopathic scoliosis (96%) who underwent primary surgery between January 1, 1981, and December 31, 1992, by one surgeon in one hospital, with use of Harrington, C-D, or Isola instrumentation were studied an average of 9 years after surgery to determine the indications for and frequency of reoperation.

RESULTS

The overall frequency of reoperation for all instrumentation types combined was 19%: Harrington, 19%; C-D, 24%; and Isola, 14%. By 6 years' follow-up the cumulative risk of reoperation by Kaplan-Meier analysis was Harrington, 14%; C-D, 21%; and Isola, 14%. (statistically nonsignificant difference). The most frequent indication for reoperation was LOSP of no apparent cause: 8% (14 patients) for all instrumentation types combined. The average interval between the initial operation and reoperation for LOSP was 46 months (range, 20-97 months). The frequency of each implant type was Harrington, 6%; C-D, 12%; and Isola, 6%. By 6 years' follow-up, the cumulative Kaplan-Meier risk for reoperation due to LOSP was Harrington, 5%; C-D, 13%; and Isola, 8% (statistically non-significant difference). Of the 14 patients who had instrumentation removal for LOSP, 10 (71%) had successful relief of pain after implant removal.

CONCLUSIONS

Occurring regardless of implant type, LOSP of no apparent cause after posterior instrumentation of scoliosis is a distinct clinical entity and is relieved by implant removal in most patients.

[Morphometric characteristics of the scoliotic spine]

GOAL

Results from a morphometric investigation performed on a rare complete scoliotic specimen are presented. The aim of the study is to describe the vertebral body wedging.

MATERIALS

The specimen used in the study presented a thoracic curve of 150 degrees Cobb angle with the apex at T8. The measures were made using 3D-computer graphics models. The wedging in the frontal and sagittal planes as well as the 3D wedging were measured. The height variation of the vertebral bodies was also measured.

RESULTS

The wedging measures show that it increases progressively with the vertebral level to reach a maximum of 27 degrees at the apex. Perdriolle has found a linear relation between the vertebral body wedging and the Cobb angle. The relation predicts a wedging of 24 degrees for 150 degrees of Cobb angle. An inflection point was identified on the vertebral end plate on the convex side. These inflection points were described by Perdriolle as being on the concave side of the vertebra.

CONCLUSION

Our measures follow the relation between the Cobb angle and the wedging of the vertebral body, even for very large Cobb angles. Furthermore, inflection points on the vertebral body were identified on the convex side as opposed to the concave side in the literature. This leads us to believe that the vertebral body wedging progressively affects the vertebral endplates.

Treatment of hip dysplasia in older children with a combined one-stage procedure

This retrospective study was conducted to determine the efficacy and complication rates associated with treating children of ambulatory age with idiopathic developmental dysplasia of the hip with open reduction and combined femoral and pelvic osteotomies. Eighteen hips were reviewed in 13 patients. The average patient age at surgery was 29 months (range, 15-117 months), with an average followup of 43 months (range, 24-78 months). Preoperative Tonnis classification identified six Class II, seven Class III, and five Class IV hips. Followup Severin classification identified 16 Class 1A and two Class 2A hips. The average center edge angle on most recent followup was 47 degrees (range, 25 degrees-70 degrees), and the acetabular index was 5 degrees (range, 0 degree-20 degrees). Avascular necrosis developed in one (5.5%) patient. Clinically, all patients were pain free with ambulation and had excellent results by McKay criteria. No patient required a second surgical procedure for recurrent subluxation or persistent acetabular dysplasia. The treatment of children who are of ambulatory age with developmental dysplasia of the hip using open reduction and combined osteotomies was safe and effective.

Osteogenic protein-1 downregulates endothelin A receptors in primary rat osteoblasts

Osteogenesis is a complex process whereby growth factors and mediators from both local and systemic sources modulate the bone-forming activities of osteoblasts. In the present study we utilized primary cultures of fetal rat calvarial cells to characterize osteoblast responsiveness to the vascular mediator endothelin-1 (ET-1) and to investigate whether ET-1 responses are regulated by osteogenic protein-1 (OP-1). We found that a 1- to 2-day exposure to OP-1 diminished ET-1 receptor ligand binding and signal transduction by downregulating ET-1 receptor mRNA expression. ET-1-mediated calcium signaling and ligand binding were completely abolished by the ETA receptor antagonist BQ-123, suggesting that ET-1 effects are mediated by this receptor. Northern analysis of total RNA revealed that ETA mRNA expression was inhibited approximately 50% by OP-1 treatment, whereas ETB receptor mRNA was not detected by this method of analysis. In OP-1-treated cultures, the magnitude and duration of ET-1 calcium signals varied among individual cells. This finding may be related to a heterogeneous OP-1 response, indicated by alkaline phosphatase induction in only a subpopulation of cells. These results suggest that modulation of osteoblast function by ET-1 occurs during distinct periods of phenotypic development and imply that downregulation of ET-1 responsiveness may be necessary for optimal bone formation in vivo.

Talocalcaneal coalition resection: a 10-year follow-up

Eight patients (nine feet) who underwent resection of persistently symptomatic talocalcaneal middle-facet coalitions were reevaluated > or = 10 years after surgery. Satisfactory results persisted in eight of nine cases with no deterioration of symptom relief. There was no loss of motion or development of degenerative joint changes. No patient required a secondary surgery. It appears that resection of symptomatic talocalcaneal coalition provides satisfactory results in the majority of patients, and its benefits are maintained 10 years after the procedure.

Current nursing practices in fever management

Data regarding fever management were obtained through a retrospective or concurrent review of the medical records of 150 patients. For 41% of the patients studied, nurses notified physicians of the fever episode. The decision to treat fever was significantly influenced by fever intensity and the drawing of blood cultures, but not by age, length of hospital stay, or the duration of the fever episode. Despite recent evidence of the protective value of fever, the majority of fever episodes were treated. Acetaminophen alone, and acetaminophen in combination with physical cooling methods, were effective in lowering fever.

The current status of scoliosis screening in North America, 1986. Results of a survey by mailed questionnaire

In May, 1986, 374 questionnaires on the multiple aspects of school screening for scoliosis were mailed to health care professionals throughout North America. An overall response rate of 73% provided objective information about screening efforts. Results showed that although there is great variability among the programs, at least some screening is done in each of the 50 United States and the District of Columbia. Previously widespread in Canada, only two Provinces currently are officially engaged in screening, Alberta (research projects only) and Prince Edward Island. The most common target population seems to be grades five through nine for both boys and girls. Lack of funding appears to be the largest factor hampering data collection. Although many varied comments and suggestions were received, most called for: 1) new recommendations for screening boys and girls at different grade levels; 2) quantitative referral criteria; 3) improved data gathering: 4) statewide uniformity within programs; and 5) improved understanding within the medical community about indications for referral and the principles of scoliosis treatment.

A modular spinal rod linkage system to provide rotational stability

The effect of cross linkage on the in vitro stability of paired Harrington distraction rods was studied in an unstable fracture model using calf spine segments. Cross linkage used in conjunction with sublaminar wires significantly improved torsional stability, improved lateral bending stability, and had no adverse affect on stability for axial, forward flexion, or extension loading compared to rods alone, rods with bridges, and wired rods.

Comparison of intravenous nitroprusside, nitroprusside-captopril, and nitroglycerin for deliberate hypotension during posterior spine fusion in adults

Three techniques for deliberate hypotension (mean arterial pressure, 60 to 70 mmHg) were prospectively compared in adults undergoing posterior spine fusion. Patients received either IV sodium nitroprusside, sodium nitroprusside with oral captopril pretreatment, or IV nitroglycerin. Patient groups were comparable in age, sex, weight, baseline hemodynamic and laboratory parameters, duration of surgery, and duration of hypotension. Absolute blood loss was significantly less in the group receiving nitroglycerin; however, there were no differences between groups when corrected for operative exposure (milliliter per spine segment exposed). Nitroprusside was effective in producing target blood pressure in all patients. Nitroglycerin was ineffective in two patients and two other patients required greater than 20 micrograms/kg/min. Both groups receiving nitroprusside developed significant postinfusion increases in arterial pressure. Blood pressure fell significantly after induction of anesthesia in patients receiving captopril. Cardiac index, heart rate, pulmonary capillary wedge pressure, intrapulmonary shunt, and arterial blood gases were comparable and did not change significantly in any group. Systemic vascular resistance fell during infusion in all groups and remained depressed after infusion in patients receiving nitroglycerin. Plasma renin activity was significantly increased in the group receiving captopril due to loss of feedback inhibition of renin release and rose significantly during infusion in those patients receiving nitroprusside alone. There were no complications. Nitroprusside with and without captopril pretreatment was associated with postoperative increases in arterial pressure, although not to hypertensive levels, probably due to loss of captopril activity after single-dose administration. The use of nitroglycerin was limited by lack of potency. There was no demonstrable clinical advantage for any of the three techniques.

Factors affecting the ambulatory status of patients with spina bifida cystica

Sixteen different factors that might affect the ambulatory status of patients with myelodysplasia after the age of five years were analyzed in ninety-eight patients using a linear regression technique (the Pearson correlation coefficient). Included in the study were fifty male and forty-eight female patients; the average age was fourteen years and four months (range, five years and nine months to thirty-one years and ten months). The sacral and fifth-lumbar paraplegics, with one exception, were all community ambulators. Fourth-lumbar paraplegics were usually functional ambulators, whose ability to walk was significantly influenced by musculoskeletal deformity of the spine, pelvis, hips, knees, feet, and ankles. Third-lumbar, first and second-lumbar, and thoracic level paraplegics usually were not functional ambulators. Ambulatory function was significantly influenced in third-lumbar paraplegics by hip deformity, in first and second-lumbar paraplegics by obesity and possibly by age, and in thoracic level paraplegics by age and by knee-foot-ankle deformities. Transitions in ambulatory status were usually to a lower functional level and were related to motivation, obesity, and musculoskeletal deformity. Ultimately, ambulatory status is probably related in large measure to the energy expenditure that is necessary to walk, but studies of energy requirements were not done. These findings emphasize the importance of controlling obesity as well as any musculoskeletal deformities that will influence the patient's ultimate walking ability.

Measurement accuracy of proximal femoral geometry using biplanar radiography

Experimental testing indicates that the neck-shaft angle of the proximal femur can be reliably measured from biplanar radiographs, but torsion cannot. Calculated torsion varies significantly from true torsion as a function of the error created by femoral rotation, while the calculated neck-shaft angle is invariant with respect to rotation even though the calculated neck-shaft angle is mathematically dependent on calculated torsion. Theoretical considerations support this finding and demonstrate for the first time why it is true. This study demonstrates that clinical measurements of frontal plane hip deformities using existing biplanar radiography are quite accurate, but clinical measurements of torsional abnormalities are unreliable. These errors can be minimized if investigators specify the angle of the lateral X-ray beam on the anteroposterior film using methods described in this paper and if patient position is radiographically verified. The magnitude and types of errors inherent in biplanar radiography should be considered in planning preoperative strategies and in postoperative assessments of hip geometry.

New technics in the operative treatment of scoliosis

Preoperative correction of scoliotic curves by traction and casting improves the results achieved by operation. Use of the halo-hoop apparatus allows controlled correction when combined with spinal osteotomies. The anterior approach to the spine allows better correction and fusion of the more difficult curves of congenital scoliosis and those associated with neurofibromatosis and myelomeningocele.

Echographic evaluation of diaphragmatic motion in intra-abdominal diseases

Movement of the diaphragm can be evaluated with diagnostic ultrasound using B- and M-mode techniques. Ultrasonic scanning is a highly sensitive method of demonstrating generalized or localized abnormalities of diaphragmatic motion and is superior to fluoroscopy in several respects. There is no exposure to ionizing radiations, and a permanent record of the excursion of the diaphragmatic surface is obtained. This method has the additional advantage of providing a two-dimensional display of the upper abdominal quadrant, which may reveal the nature of the underlying disease process.