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Dive into the research topics where Katherine S. Tzou is active.

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Featured researches published by Katherine S. Tzou.


Journal of Clinical Oncology | 2016

Improved Metastasis-Free and Survival Outcomes With Early Salvage Radiotherapy in Men With Detectable Prostate-Specific Antigen After Prostatectomy for Prostate Cancer

Bradley J. Stish; Thomas M. Pisansky; William S. Harmsen; Brian J. Davis; Katherine S. Tzou; Richard Choo; Steven J. Buskirk

Purpose To describe outcomes of salvage radiotherapy (SRT) for men with detectable prostate-specific antigen (PSA) after radical prostatectomy for prostate cancer and identify associations with outcomes. Patients and Methods A total of 1,106 patients received SRT between January 1987 and July 2013, with median follow-up 8.9 years. Outcomes were estimated using Kaplan-Meier for overall survival (OS) and cumulative incidence for biochemical recurrence (BcR), distant metastases (DM), and cause-specific mortality (CSM). Variable associations with outcomes used Cox or Fine-Gray methods, as appropriate. Multiple variable analyses used backward selection with P < .05 for retention. Results In multiple variable analyses, pathologic tumor stage, Gleason score, and pre-SRT PSA were associated with BcR, DM, CSM, and OS; androgen suppression and SRT doses > 68 Gy were associated with BcR; and age was associated with OS. Each pre-SRT PSA doubling increased significantly the relative risk of BcR (hazard ratio [HR], 1.30; P < .001), DM (HR, 1.32; P < .001), CSM (HR, 1.40; P < .001), and all-cause mortality (HR, 1.12; P = .02). Using a pre-SRT PSA cutoff ≤ 0.5 versus > 0.5 ng/mL, 5-year and 10-year cumulative incidences for BcR were 42% versus 56% and 60% versus 68% ( P < .001), DM 7% versus 14% and 13% versus 25% ( P < .001), CSM 1% versus 4% and 6% versus 13% ( P < .001), and OS of 94% versus 92% and 83% versus 73% ( P > .05). Conclusion SRT outcomes are in part affected by factors associated with prostatectomy findings but may be positively affected by using SRT at lower PSA levels, including reductions in BcR, DM, CSM, and all-cause mortality. These findings argue against prolonged monitoring of detectable postprostatectomy PSA levels that delay initiation of SRT.


International Journal of Surgical Oncology | 2012

Ductal carcinoma in situ of the breast

Richard J. Lee; Laura A. Vallow; Sarah A. McLaughlin; Katherine S. Tzou; Stephanie L. Hines; Jennifer L. Peterson

Ductal carcinoma in situ (DCIS) of the breast represents a complex, heterogeneous pathologic condition in which malignant epithelial cells are confined within the ducts of the breast without evidence of invasion. The increased use of screening mammography has led to a significant shift in the diagnosis of DCIS, accounting for approximately 27% of all newly diagnosed cases of breast cancer in 2011, with an overall increase in incidence. As the incidence of DCIS increases, the treatment options continue to evolve. Consistent pathologic evaluation is crucial in optimizing treatment recommendations. Surgical treatment options include breast-conserving surgery (BCS) and mastectomy. Postoperative radiation therapy in combination with breast-conserving surgery is considered the standard of care with demonstrated decrease in local recurrence with the addition of radiation therapy. The role of endocrine therapy is currently being evaluated. The optimization of diagnostic imaging, treatment with regard to pathological risk assessment, and the role of partial breast irradiation continue to evolve.


Expert Review of Anticancer Therapy | 2011

Treatment of men with rising prostate-specific antigen levels following radical prostatectomy

Katherine S. Tzou; Winston Tan; Steven J. Buskirk

Approximately one-third of patients who undergo radical prostatectomy for prostate cancer will develop a detectable prostate-specific antigen (PSA) level within 10 years. Biochemical recurrence of disease is defined as a rising PSA level in the absence of clinical or radiographic evidence of disease. Management of PSA recurrence is controversial, as prostate cancer may take an indolent course, or it may aggressively develop into metastatic disease. The only potentially curative treatment for biochemical failure after prostatectomy is salvage radiotherapy. Noncurative treatment options include hormone therapy or clinical trials of a novel systemic agent. This article will address management options for a rising PSA level after prostatectomy, as well as ongoing studies exploring molecular biomarkers as prognostic tumor markers and potential targets for prostate cancer therapy.


Medical Dosimetry | 2014

Image-guided intensity-modulated radiotherapy for prostate cancer: Dose constraints for the anterior rectal wall to minimize rectal toxicity.

Jennifer L. Peterson; Steven J. Buskirk; Michael G. Heckman; Nancy N. Diehl; Johnny Ray Bernard; Katherine S. Tzou; Henry E. Casale; Louis P. Bellefontaine; C. Serago; Siyong Kim; Laura A. Vallow; Larry C. Daugherty; Stephen J. Ko

Rectal adverse events (AEs) are a major concern with definitive radiotherapy (RT) treatment for prostate cancer. The anterior rectal wall is at the greatest risk of injury as it lies closest to the target volume and receives the highest dose of RT. This study evaluated the absolute volume of anterior rectal wall receiving a high dose to identify potential ideal dose constraints that can minimize rectal AEs. A total of 111 consecutive patients with Stage T1c to T3a N0 M0 prostate cancer who underwent image-guided intensity-modulated RT at our institution were included. AEs were graded according to the Common Terminology Criteria for Adverse Events, version 4.0. The volume of anterior rectal wall receiving 5 to 80Gy in 2.5-Gy increments was determined. Multivariable Cox regression models were used to identify cut points in these volumes that led to an increased risk of early and late rectal AEs. Early AEs occurred in most patients (88%); however, relatively few of them (13%) were grade ≥2. At 5 years, the cumulative incidence of late rectal AEs was 37%, with only 5% being grade ≥2. For almost all RT doses, we identified a threshold of irradiated absolute volume of anterior rectal wall above which there was at least a trend toward a significantly higher rate of AEs. Most strikingly, patients with more than 1.29, 0.73, or 0.45cm(3) of anterior rectal wall exposed to radiation doses of 67.5, 70, or 72.5Gy, respectively, had a significantly increased risk of late AEs (relative risks [RR]: 2.18 to 2.72; p ≤ 0.041) and of grade ≥ 2 early AEs (RR: 6.36 to 6.48; p = 0.004). Our study provides evidence that definitive image-guided intensity-modulated radiotherapy (IG-IMRT) for prostate cancer is well tolerated and also identifies dose thresholds for the absolute volume of anterior rectal wall above which patients are at greater risk of early and late complications.


Melanoma Research | 2016

Treatment of in-transit and metastatic melanoma in two patients treated with ipilimumab and topical imiquimod.

Richard W. Joseph; Mark A. Cappel; Katherine S. Tzou; Sanjay P. Bagaria; Cheryl Gilstrap; Abhisek Swaika; Anokhi Jambusaria-Pahlajani

Checkpoint blockade inhibitors have revolutionized the treatment of metastatic melanoma. Despite the success of these agents in improving the overall survival of patients with metastatic melanoma, not all patients achieve clinical benefit, leaving room for improvement. The presence of cutaneous metastases in patients with metastatic melanoma provides the unique opportunity to treat the cutaneous lesions with a local modality while simultaneously treating systemic disease with systemic therapy. Herein, we describe the treatment of two patients with both in-transit and metastatic melanoma with the combination of the topical toll-like receptor 7 agonist imiquimod with systemic ipilimumab. Both patients appeared to have progressed and developed new cutaneous and systemic metastases while on single agent ipilimumab only to respond when started on topical imiquimod. Both patients tolerated the combination of imiquimod and ipilimumab without serious adverse events, and both patients had excellent clinical responses. These cases provide a proof of principle of the possibility of the combination of toll-like receptor 7 agonists with immune checkpoint blockade inhibitors.


Clinical Genitourinary Cancer | 2017

Factors Associated With Survival Following Radium-223 Treatment for Metastatic Castration-resistant Prostate Cancer

William W. Wong; Eric M. Anderson; Homan Mohammadi; Thomas B. Daniels; Steve E. Schild; Sameer R. Keole; C. Richard Choo; Katherine S. Tzou; Alan H. Bryce; Thai H. Ho; Fernando Quevedo; Sujay A. Vora

Micro‐Abstract The outcomes of 64 patients with metastatic castration‐resistant prostate cancer after treatment with radium‐223 were analyzed. Four factors were identified to be associated with survival in multivariate analysis. Future studies to evaluate earlier use of this radiopharmaceutical in newly diagnosed metastatic prostate cancer when the disease is sensitive to androgen deprivation therapy would be warranted. Background: Radium‐223 (223Ra) improves survival in patients with metastatic castration‐resistant prostate cancer (mCRPC). This retrospective analysis was performed to better understand its efficacy in routine clinical practice and identify factors associated with survival. Materials and Methods: Sixty‐four patients with mCRPC who received 223Ra between 2013 and 2015 were the basis of this retrospective study. Clinical outcomes and patient characteristics were obtained. Potential prognostic factors for survival were evaluated by univariate analysis using the log‐rank test and multivariate analysis using the Cox proportional hazard method. Results: The median survival was 12.9 months. Twenty‐one patients (33%) developed a skeletal event, and the median time to the first skeletal event was 4.4 months. In univariate analysis, factors significantly associated with survival included: no prior chemotherapy, ≤ 5 bone metastases, baseline prostate‐specific antigen (PSA) ≤ 36 ng/mL, baseline alkaline phosphatase (ALP) < 115 U/L, baseline hemoglobin > 12 g/dL, ALP response after 223Ra treatment, PSA decrease during 223Ra treatment, and absence of > 25% PSA increase during 223Ra treatment. In multivariate analysis, 4 factors remained significant: no prior chemotherapy, ≤ 5 bone metastases, baseline ALP < 115 U/L, and ALP response after 223Ra treatment. Conclusion: When 223Ra is administered in routine clinical practice, clinical outcomes can be more variable than those reported in the randomized study owing to patient heterogeneity. Four factors were identified to be significantly associated with survival after 223Ra treatment. These pretreatment factors may be used as stratification factors in future studies to investigate whether 223Ra would be more effective for patients with newly diagnosed metastatic disease that is sensitive to androgen deprivation therapy.


Advances in radiation oncology | 2017

Patient-reported distress and survival among patients receiving definitive radiation therapy

Y. Habboush; Robert P. Shannon; Shehzad K. Niazi; Laeticia Hollant; Megan Single; Katherine Gaines; Bridget Smart; Nicolette T. Chimato; Michael G. Heckman; Steven J. Buskirk; Laura A. Vallow; Katherine S. Tzou; Stephen J. Ko; Jennifer L. Peterson; Heather Biers; Atiya Day; Kimberly Nelson; Jeff A. Sloan; Michele Y. Halyard; Robert C. Miller

Objective Patient-reported distress (PRD) has not been well assessed in association with survival after radiation therapy (RT). The aims of this study were to evaluate the association between PRD level and survival after definitive RT and to identify the main causes of distress in definitive RT patients. Methods and materials A total of 678 consecutive patients receiving definitive RT at our institution from April 2012 through May 2015 were included. All patients answered a PRD questionnaire that contained 30 items related to possible causes of distress, which could be rated from 1 (no distress) to 5 (high distress). Additionally, patients were asked to rate their overall distress level from 0 (no distress) to 10 (extreme distress). This overall distress level was our primary patient-reported distress measure and was examined as a continuous variable and as a categorical variable with 3 PRD levels (low, 0-3 [n = 295]; moderate, 4-6 [n = 222]; and high, 7-10 [n = 161]). Results As a continuous variable in multivariable Cox regression analysis, a higher overall PRD level was associated with poorer survival after RT (hazard ratio [HR], 1.39; P = .004). As a categorical variable, compared with patients with low distress, survival was poorer for patients with moderate distress (HR, 1.62; P = .038) or high distress (HR, 1.49; P = .12), but the latter difference was not significant. When the moderate and high distress levels were combined, survival was significantly poorer compared with the low distress level (HR, 1.57; P = .034). The top 5 specific causes of distress that patients mentioned were “How I feel during treatment,” “Fatigue,” “Out-of-pocket medical costs,” “Pain that affects my daily functioning,” and “Sleep difficulties.” Conclusions PRD before or during RT is a prognostic factor associated with decreased survival. Distress screening guidelines and interventions should be implemented for patients receiving definitive RT.


Rare Tumors | 2015

Management of Metastatic Apocrine Hidradenocarcinoma with Chemotherapy and Radiation.

D. Miller; Jennifer L. Peterson; Steven J. Buskirk; Laura A. Vallow; Randy Ta; Richard W. Joseph; Murli Krishna; Stephen J. Ko; Katherine S. Tzou

Hidradenocarcinoma is a rare aggressive form of cutaneous adnexal skin carcinoma originating from the sweat gland. Due to its low incidence, prognostic and treatment strategies are still being explored both for primary and advanced disease. This tumor most often presents as either solid or cystic appearing subcutaneous nodules, which may be associated with pruritus or ulceration. To date the mainstay of treatment for local disease has been surgical excision; however, the paucity of historical data available has shown that these tumors often behave aggressively with high rates of local recurrence, metastasis, and poor overall outcomes. There are few case reports describing the utility of radiation therapy in the treatment of hidradenocarcinoma. Herein, we present a case of metastatic apocrine hidradenocarcinoma in a 32-year-old Caucasian male. The patient initially underwent excisional biopsy which confirmed the diagnosis of poorly differentiated, highly infiltrative, apocrine hidradenocarcinoma. He received systemic chemotherapy for metastatic disease, followed by radiation therapy to areas of grossly palpable adenopathy. Prior to radiation therapy the patient had an enlarged hypermetabolic conglomerate of lymph nodes in the right axilla, and borderline enlarged low activity nodes within the left axilla. He received 3 cycles of chemotherapy followed by tamoxifen and radiation therapy (50.4 Gy in 28 fractions) to areas of progressive disease in the bilateral axilla, lower neck, and axillary skin. Following treatment, the patient had complete resolution of skin nodules and improvement of his pruritus. While the role of radiation therapy in the treatment of hidradenocarcinoma has not been well established, this case report demonstrated the potential benefit of external beam radiotherapy in the management of this rare disease.


Rare Tumors | 2016

Small cell carcinoma of the prostate in an elderly patient: a case report and review of the literature

Dale Alan Whitaker; D. Miller; Niveditha Jagadesh; G. Strong; L. Hintenlang; William Schenk; Gregory A. Broderick; Katherine S. Tzou; Steven J. Buskirk

Prostate cancer is the most common malignancy of men in the United States. Small-cell carcinoma (SCC), which typically presents as an aggressive lung malignancy, is a rare diagnosis within the setting of prostate cancer pathology. Due to its limited prevalence, little information regarding the treatment and prognosis of this disease in large populations is available. To date our current knowledge base is largely limited to case reports and retrospective case reviews. The mainstay of treatment for this particular histology most often involves a multimodality approach utilizing chemotherapy in conjunction with radiation therapy, androgen deprivation therapy, or prostatectomy. Here we present the case of an elderly 89-year-old Caucasian male who was diagnosed with SCC of the prostate. Despite proceeding with a course of definitive radiotherapy, the patient experienced rapid progression of disease and ultimately elected to discontinue radiation therapy and receive hospice care.


International Scholarly Research Notices | 2013

Evaluation of Serum Calcium as a Predictor of Biochemical Recurrence following Salvage Radiation Therapy for Prostate Cancer

Jennifer L. Peterson; Steven J. Buskirk; Michael G. Heckman; Alexander S. Parker; Nancy N. Diehl; Katherine S. Tzou; Nitesh N. Paryani; Stephen J. Ko; Larry C. Daugherty; Laura A. Vallow; Thomas M. Pisansky

Background. Previous reports have shown a positive association between serum calcium level and prostate cancer mortality. However, there is no data regarding whether higher serum calcium levels are associated with increased risk of biochemical recurrence (BCR) following salvage radiation therapy (SRT) for prostate cancer. Herein, we evaluate the association between pretreatment serum calcium levels and BCR in a cohort of men who underwent SRT. Methods. We evaluated 165 patients who underwent SRT at our institution. Median dose was 65.0 Gy (range: 54.0–72.4 Gy). We considered serum calcium as both a continuous variable and a 3-level categorical variable (low [≤9.0 mg/dL], moderate [>9.0 mg/dL and ≤9.35 mg/dL], and high [>9.35 mg/dL]) based on sample tertiles. Results. We observed no evidence of a linear association between serum calcium and BCR (relative risk (RR): 0.96, P = 0.76). Compared to men with low calcium, there was no significantly increased risk of BCR for men with moderate (RR: 0.94, P = 0.79) or high (RR: 1.08, P = 0.76) serum calcium levels. Adjustment for clinical, pathological, and SRT characteristics in multivariable analyses did not alter these findings. Conclusion. Our results provide evidence that pretreatment serum calcium is unlikely to be a useful tool in predicting BCR risk following SRT.

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