The evolution of chemoresistance is a fundamental characteristic of cancer that ultimately hampers its clinical management. However, it may be possible to improve patient outcomes significantly by a better understanding of resistance mechanisms, which cancers rely upon during the evolution to an untreatable state. Here we report an essential role of the stem cell reprogramming factor, PBX1, in mediating chemoresistance in ovarian carcinomas. In the clinical setting, high levels of PBX1 expression correlated with shorter survival in post-chemotherapy ovarian cancer patients. In tumor cells with low endogenous levels of PBX1, its enforced expression promoted cancer stem cell-like phenotypes, including most notably an increase in resistance to platinum-based therapy used most commonly for treating this disease. Conversely, silencing PBX1 in platinum-resistant cells that overexpressed PBX1 sensitized them to platinum treatment and reduced their stem-like properties. An analysis of published genome-wide chromatin immunoprecipitation data indicated that PBX1 binds directly to promoters of genes involved in stem cell maintenance and the response to tissue injury. We confirmed direct regulation of one of these genes, STAT3, demonstrating that the PBX1 binding motif at its promoter acted to positively regulate STAT3 transcription. We further demonstrated that a STAT3/JAK2 inhibitor could potently sensitize platinum-resistant cells to carboplatin and suppress their growth in vivo Our findings offer a mechanistic rationale to target the PBX1/STAT3 axis to antagonize a key mechanism of chemoresistance in ovarian cancers and possibly other human cancers. Cancer Res; 76(21); 6351-61. ©2016 AACR.

A recent ASCO workforce study projects a significant shortage of oncologists in the U.S. by 2020, especially in rural/underserved (R/US) areas. The current study aim was to determine the patterns of distribution of U.S. gynecologic oncologists (GO) and to identify provider-based attitudes and barriers that may prevent GOs from practicing in R/US regions. U.S. GOs (n = 743) were electronically solicited to participate in an on-line survey regarding geographic distribution and participation in outreach care. A total of 320 GOs (43%) responded; median age range was 35-45 years and 57% were male. Most practiced in an urban setting (72%) at a university hospital (43%). Only 13% of GOs practiced in an area with a population < 50,000. A desire to remain in academics and exposure to senior-level mentorship were the factors most influencing initial practice location. Approximately 50% believed geographic disparities exist in GO workforce distribution that pose access barriers to care; however, 39% "strongly agreed" that cancer patients who live in R/US regions should travel to urban cancer centers to receive care within a center of excellence model. GOs who practice within 50 miles of only 0-5 other GOs were more likely to provide R/US care compared to those practicing within 50 miles of ≥ 10 GOs (p < 0.0001). Most (39%) believed the major barriers to providing cancer care in R/US areas were volume and systems-based. Most also believed the best solution was a hybrid approach, with coordination of local and centralized cancer care services. Among GOs, a self-reported rural-urban disparity exists in the density of gynecologic oncologists. These study findings may help address barriers to providing cancer care in R/US practice environments.

Purpose

The Sedlis criteria define risk factors for recurrence warranting post-hysterectomy radiation for early-stage cervical cancer; however, these factors were defined for squamous cell carcinoma (SCC) at an estimated recurrence risk of ≥30%. Our study evaluates and compares risk factors for recurrence for cervical SCC compared with adenocarcinoma (AC) and develops histology-specific nomograms to estimate risk of recurrence and guide adjuvant treatment.

Methods

We performed an ancillary analysis of GOG 49, 92, and 141, and included stage I patients who were surgically managed and received no neoadjuvant/adjuvant therapy. Multivariable Cox proportional hazards models were used to evaluate independent risk factors for recurrence by histology and to generate prognostic histology-specific nomograms for 3-year recurrence risk.

Results

We identified 715 patients with SCC and 105 with AC; 20% with SCC and 17% with AC recurred. For SCC, lymphvascular space invasion (LVSI: HR 1.58, CI 1.12-2.22), tumor size (TS ≥4 cm: HR 2.67, CI 1.67-4.29), and depth of invasion (DOI; middle 1/3, HR 4.31, CI 1.81-10.26; deep 1/3, HR 7.05, CI 2.99-16.64) were associated with recurrence. For AC, only TS ≥4 cm, was associated with recurrence (HR 4.69, CI 1.25-17.63). For both histologies, there was an interaction effect between TS and LVSI. For those with SCC, DOI was most associated with recurrence (16% risk); for AC, TS conferred a 15% risk with negative LVSI versus a 25% risk with positive LVSI.

Conclusions

Current treatment standards are based on the Sedlis criteria, specifically derived from data on SCC. However, risk factors for recurrence differ for squamous cell and adenocarcinoma of the cervix. Histology-specific nomograms accurately and linearly represent risk of recurrence for both SCC and AC tumors and may provide a more contemporary and tailored tool for clinicians to base adjuvant treatment recommendations to their patients with cervical cancer.

The authors regret that the version of Table 3 originally published in this article was incorrect. The online version has now been updated and the correct table can be found below. The authors would like to apologise for any inconvenience caused. Table 3. Comparison of 3 yr RFS, nomogram recurrence risk, and Sedlis criteria for predictor variable combinations. [Table Presented]

Objectives

We sought to analyze the clinicopathologic features, recurrence patterns and survival outcomes of women with high-grade uterine cancer (UC) enrolled on The Gynecologic Oncology Group (GOG) LAP2 trial.

Methods

This is a post-hoc analysis of LAP-2 patients with grade 3 endometrioid adenocarcinoma (ENDO), uterine serous (USC), clear cell (CC) and carcinosarcoma (CS). Demographics, clinicopathologic features, and recurrence patterns, were compared by histology and surgical approach. Progression-free survival (PFS) and overall survival (OS) were estimated using the Kaplan-Meier method.

Results

Of the 2600 patients enrolled in LAP-2, 753 patients had high-grade UC: 350 had ENDO, 289 had USC, 42 had CC and 72 had CS. Compared with the ENDO cohort, those with other high-grade subtypes were older (p<0.001) and were more likely to have positive peritoneal cytology (p<0.001), positive lymph nodes (p=0.05) and higher disease stage on final pathology (p<0.001). With a median follow-up time of 60months, compared to patients with ENDO, those with USC, CCC and CS subtypes had higher recurrence rates (p<0.001), extra-pelvic recurrences (p<0.001) and poorer PFS (p<0.001) and OS (p<0.001). Those diagnosed with USC and CS experienced the worst survival outcomes (p=0.003). Patterns of recurrence and survival were not different in those staged with LSC vs LAP. On multivariable analysis, age, stage, pelvic washings and Type II histology were independently and adversely associated with survival.

Conclusions

Women with apparent early-stage, USC and CS histologies have poorer outcomes than women with grade 3 endometrioid adenocarcinoma. Patterns of recurrence and survival were not impacted by surgical approach.