The subspecialty of gynecologic oncology was formalized less than 50 years ago with the creation of the Society of Gynecologic Oncology and subspecialty training and board certification. The formation of the Gynecologic Oncology Group (GOG) – and the many clinical trials spearheaded by that group – has further advanced evidence-based treatments, resulting in improved survival outcomes, quality of life, and preventive strategies.
While it is not possible to provide a comprehensive and exhaustive review of all of the advances, we hope to highlight many of the notable advances in this article.
Cervical cancer is the fourth most common cancer in women worldwide with 528,000 new cases in 2012. The majority of cervical cancer cases are caused by infection with human papillomavirus (HPV). While the standard therapies for cervical cancer have been long established (radical hysterectomy for stage I and radiation therapy for locally advanced disease), one of the most significant advances in the past 50 years was the addition of radiation-sensitizing chemotherapy (cisplatin) administered concurrently with radiation therapy.
In randomized trials in both early and advanced cervical cancer, the risk of death was reduced by 30%-50%. These studies changed the paradigm for the treatment of cervical cancer (N Engl J Med. 1999 Apr 15;340:1137-43; N Engl J Med. 1999 Apr 15;340:1144-53; J Clin Oncol. 2000 Apr;18:1606-13).
Future studies evaluating biologic adjuncts or additional chemotherapy are currently underway or awaiting data maturation.
The American Society of Clinical Oncology (ASCO) highlighted the “Top 5 advances in 50 years of Modern Oncology” in 2014, and second on the list was the approval of the HPV vaccine to prevent cervical cancer. Vaccines have been developed that can protect against types 2, 4 or 9 of HPV. In a 2014 study, depending on vaccination coverage, the relative number of cervical cancer cases avoided was 34% in Africa, 27% for America, 26% for Asia, 21% for Europe, and worldwide was estimated at 27% (Vaccine. 2014 Feb 3;32:733-9).
While the benefit from HPV vaccination has been proven, in the United States, only about a third of eligible girls and women have been vaccinated. Efforts should focus on expanding vaccination penetration to eligible girls, boys, women, and men.
Endometrial cancer is the most common gynecologic malignancy in the United States with an estimated 54,870 cases and 10,170 deaths annually. Notable advances in the management of women with endometrial cancer have arisen because of a better understanding that there are two types of endometrial cancer – type I and type II.
The type I endometrial cancers tend to be associated with lower stage of disease at the time of diagnosis and fewer recurrences, while type II endometrial cancer is associated with worse outcomes.
Tailoring the surgical approaches and adjuvant therapy for women with endometrial cancer has led to improved outcomes. The GOG conducted a large prospective randomized trial of laparotomy versus laparoscopic surgical staging for women with clinical early-stage endometrial cancer (LAP2). Laparoscopy was associated with improved perioperative outcomes and was found to be noninferior to laparotomy with regards to survival outcomes (J Clin Oncol. 2012 Mar 1;30:695-700). Therefore, minimally invasive surgery has become widely accepted for the surgical staging of women with endometrial cancer.
Appropriate surgical staging allows for tailoring of postoperative adjuvant therapy. The current evidence suggests that vaginal brachytherapy should be the adjuvant treatment of choice over whole pelvic radiation in women with early-stage endometrial cancer (Lancet. 2010 Mar 6;375:816-23). Studies are underway to evaluate the role of both adjuvant radiation and chemotherapy in women with early-stage type II endometrial cancer who are felt to be at high risk for recurrent disease, as well as how to improve on the therapeutic options for women with advanced or recurrent disease.
Epithelial ovarian cancer is the most deadly gynecologic malignancy in the United States with 21,290 cases and 14,180 deaths in 2015. The concept of ovarian tumor debulking was first described by Dr. Joe Meigs in 1934, but did not gain traction until the mid-1970s when Dr. C. Thomas Griffiths published his work (Natl Cancer Inst Monogr. 1975 Oct;42:101-4).
While there are no randomized trials proving that surgical cytoreduction improves overall survival, most retrospective studies support this concept. In 2009, Chi et al. showed improved median survival in women with ovarian cancer based on the increased percentage of women who underwent optimal cytoreduction (Gynecol Oncol. 2009 Jul;114:26-31). This has led to modifications of surgical techniques and surgical goals with an effort to maximally cytoreduce all of the visible disease.
While initial surgical debulking is the goal, there are circumstances when a different approach may be indicated. Vergote et al. conducted a prospective randomized trial of 670 women with advanced ovarian cancer. In this study, neoadjuvant chemotherapy followed by interval debulking was not inferior to primary debulking followed by chemotherapy with regards to progression-free survival and overall survival. However, initial surgery was associated with increased surgical complications and perioperative mortality as compared with interval surgery. Therefore, in women who are not felt to be candidates for optimal cytoreduction, neoadjuvant chemotherapy followed by interval surgery may be an appropriate treatment strategy (N Engl J Med. 2010 Sep 2;363:943-53.).
There have been several notable advances and a series of randomized trials – predominately conducted by the GOG – that have resulted in improved overall survival and progression-free interval in women with ovarian cancer. However, none are as significant as the discovery of paclitaxel and platinum-based chemotherapy (cisplatin and carboplatin).
In 1962, samples of the Pacific Yew’s bark were collected and, 2 years later, the extracts from this bark were found to have cytotoxic activity. There were initial difficulties suspending the drug in solution; however, ultimately a formulation in ethanol, cremophor, and saline was found to be effective. In 1984, the National Cancer Institute began clinical trials of paclitaxel and it was found to be highly effective in ovarian cancer. In 1992, it was approved for the treatment of ovarian cancer.
Cisplatin was approved in 1978. Carboplatin entered clinical trials in 1982 and was approved for women with recurrent ovarian cancer in 1989.
There were a series of trials beginning in the late 1980s that established the role of platinum agents and led us to GOG 111. This trial evaluated cisplatin with either cyclophosphamide or paclitaxel. The paclitaxel combination was superior and in 2003 two trials were published that solidified carboplatin and paclitaxel as the cornerstone in the treatment of women with ovarian cancer (J Clin Oncol. 2003 Sep 1;21:3194-200; J Natl Cancer Inst. 2003 Sep 3;95:1320-9).
What has most recently been debated is the route and schedule for both paclitaxel and the platinum agents. In January 2006, the National Cancer Institute released a Clinical Announcement regarding the role of intraperitoneal (IP) chemotherapy for the treatment of women with optimally debulked ovarian cancer. Of the six trials included in the announcement, four trials showed a benefit for progression-free survival and five studies showed an improvement in overall survival. Armstrong et al (GOG 172) showed a 16-month improvement in overall survival with intravenous (IV) paclitaxel, IP cisplatin, and IP paclitaxel. IP chemotherapy has not been universally embraced by physicians and patients in part because of its toxicity, treatment schedule, and the fact that no IP regimen has been compared with the current standard of IV carboplatin and paclitaxel (N Engl J Med. 2006 Jan 5;354:34-43).
While there have been improvements in 5-year survival over time, most women with advanced ovarian cancer will undergo additional chemotherapy in order to achieve subsequent remissions or maintain stability of disease. Other drugs that have Food and Drug Administration approval in the setting of recurrent ovarian cancer include topotecan, liposomal doxorubicin, gemcitabine, bevacizumab, altretamine, carboplatin, cisplatin, cyclophosphamide, and melphalan. Olaparib was recently approved as monotherapy in women with a germline BRCA-mutation who had received three or more prior lines of chemotherapy.
Minimally Invasive Surgery
Over the last 30 years, minimally invasive surgery (MIS) in gynecologic oncology, particularly for endometrial cancer, has gone from a niche procedure to the standard of care. The introduction of laparoscopy into gynecologic oncology started in the early 1990s. In a series of 59 women undergoing laparoscopy for endometrial cancer, Childers et al. demonstrated feasibility of the technique and low laparotomy conversion rates (Gynecol Oncol. 1993 Oct;51:33-8.). The GOG trial, LAP2, supported the equivalent oncologic outcomes of MIS versus laparotomy for the treatment of endometrial cancer. While many surgeons and centers offered laparoscopic surgery, there were issues with the learning curve that limited its widespread use.
In 2005, the FDA approval of the robotic platform for gynecologic surgery resulted in at least a doubling of the proportion of endometrial cancer patients treated with MIS (Int J Med Robot. 2009 Dec;5:392-7.). In 2012, the Society of Gynecologic Oncology published a consensus statement regarding robotic-assisted surgery in gynecologic oncology (Gynecol Oncol. 2012 Feb;124:180-4.). This review highlights the advantages of the robotics platform with regards to expanding MIS to women with cervical and ovarian cancer; the improvements in outcomes in the obese woman with endometrial cancer; and that the learning curve for robotic surgery is shorter than for traditional laparoscopy. Issues requiring further research include cost analysis as the cost of the new technology decreases, and opportunities for improvement in patient and physician quality of life.
Sentinel Node Mapping
The rationale for sentinel node mapping is that if one or more sentinel lymph nodes is/are negative for malignancy, then the other regional lymph nodes will also be negative. This would thereby avoid the need for a complete lymph node dissection and its resultant complications, including chronic lymphedema. Much of the work pioneering this strategy has been in breast cancer and melanoma, but data are rapidly emerging for these techniques in gynecologic malignancies.
Candidates for sentinel lymph node biopsy for vulvar cancer include those with a lesion more than 1mm in depth, a tumor less than 4 cm in size, and no obvious metastatic disease on exam or preoperative imaging. Additionally, recommendations have been made regarding case volume in order to achieve limited numbers of false-negative results and to maintain competency. In the study by Van der Zee et al. of 403 patients (623 groins) who underwent sentinel node procedures, the false-negative rate was 0-2%. The overall survival rate was 97% at 3 years (J Clin Oncol. 2008 Feb 20;26:884-9). However, a more recent data from the Gynecologic Oncology Group (GOG 173) showed a slightly higher false-negative rate of 8% (J Clin Oncol. 2012 Nov 1;30:3786-91). Overall survival data are pending from this study.
While sentinel lymph node mapping for endometrial cancer has been feasible for many years and has been well described, the questioned role of completed lymphadenectomy for early-stage endometrial cancer has led to a resurgence of interest in these techniques. While blue dye and radiolabeled tracer methods have historically been the most popular mapping solutions, the advent of endoscopic near-infrared imaging, with its higher sensitivity and good depth penetration, has added options. Indocyanine green fluorescence can be easily detected during robotic surgery and as experience with these techniques increase, successful mapping and sensitivity will increase.
While hereditary cancer syndromes have been recognized for many years, detecting the genetic mutations that may increase an individual’s risk of developing a malignancy were not elucidated until the early 1990s. In gynecologic oncology, the most commonly encountered syndromes involve mutations in BRCA1 and BRCA2 and hereditary non–polyposis colorectal cancer, which causes mutations in DNA mismatch-repair genes and increase the risk of endometrial and ovarian cancer.
The SGO recently published a statement on risk assessment for inherited gynecologic cancer predispositions. In this statement “the evaluation for the presence of a hereditary cancer syndrome enables physicians to provide individualized and quantified assessment of cancer risk, as well as options for tailored screening and preventions strategies that may reduce morbidity associated with the development of malignancy” (Gynecol Oncol. 2015 Jan;136:3-7). Beyond risk-reducing salpingo-oophorectomy, therapeutic strategies targeting patients with germline mutations have been developed (PARP inhibitors in BRCA-mutated women with ovarian cancer).
In August 2015, ASCO released an updated policy statement on genetic and genomic testing for cancer susceptibility and highlighted five key areas: germ-line implications of somatic mutation profiling; multigene panel testing for cancer susceptibility; quality assurance in genetic testing; education for oncology professionals; and access to cancer genetic services.
Rounding out ASCO’s “Top 5 advances in 50 years of Modern Oncology” was the improvement in patients’ quality of life from supportive therapies, in particular antinausea medications.
Several of the agents commonly used in gynecologic oncology rate high (cisplatin) to moderate (carboplatin, cyclophosphamide, doxorubicin, ifosfamide) with regards to emetogenicity. The advent of 5-HT3 receptor antagonists (for example, ondansetron) has significantly improved the quality of life of patients undergoing cytotoxic chemotherapy. In addition to improving quality of life, the decrease in nausea and vomiting can also decrease life-threatening complications such as dehydration and electrolyte imbalance. Both ASCO and the National Comprehensive Cancer Network both have guidelines for the management of nausea and vomiting in patients undergoing chemotherapy.
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