Annals of Oncology Advance Access originally published online on March 19, 2008
Annals of Oncology 2008 19(7):1278-1283; doi:10.1093/annonc/mdn041
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gynecologic tumors |
The role of DNA ploidy in postoperative management of stage I endometrial cancer
1 Division of Gynecology and Obstetrics
2 Department of Surgical Pathology, IRCCS San Raffaele Hospital
3 Department of Mathematics, University of Milan, Milan, Italy
* Correspondence to: Dr S. Montoli, Division of Gynecology and Obstetrics, Università "Vita e Salute", San Raffaele Hospital, Via Olgettina 60, 20132 Milano, Italy. Tel: +39-02-26432652; Fax: +39-02-26432759; E-mail: montoli.serena{at}hsr.it
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Abstract |
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Background: Definition of high-risk stage I endometrial cancer (EC) patients who might benefit from adjuvant therapy (AT) is controversial. Decision is on the basis of traditional prognostic factors. We report our experience in which ploidy has found to play a role in clinical practice since 1999.
Patients and methods: Two hundred and twenty-two patients with stage I EC with a median follow-up of 4.57 years were studied. After primary surgery, patients are chronologically divided in group A, from 1990 to 1998 (n = 141), receiving AT in IC stage and group B, from 1999 to 2003 (n = 81), receiving AT in case of DNA index >1.2 or stage IC grade 3 with unknown lymph node status. We analyzed prognostic factors, survival and relapse rate of the two groups.
Results: Since ploidy was introduced as a decision-making factor, only 30.6% (n = 11) of patients with stage IC received AT. Despite this considerable decrease of AT, no tumor-related deaths were reported in the group of patients with diploid IC stage who did not receive AT. Only DNA ploidy and age at diagnosis were independent predictors of overall survival.
Conclusions: Our results indicate the important role of ploidy in order to identify high-risk patients who need AT and avoid overtreatment.
Key words: adjuvant treatment, endometrial cancer, ploidy, prognostic factors
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introduction |
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Management of stage I endometrial carcinoma varies among institutions, [1] and actually there is no consensus on evidence-based postoperative treatment.
Adjuvant radiotherapy (RT) remains the standard postoperative treatment for high-risk patients, but the impact on survival is not clearly defined [2–4].
An accurate prognostic assessment is required to identify groups of patients who may benefit from adjuvant therapy (AT). In endometrioid stage I adenocarcinoma, grade of differentiation, depth of myometrial invasion and lymph node status are well-known prognostic indicators. None of these traditional prognostic factors, however, allows a very accurate stratification of patients, resulting in unnecessary AT for many patients.
DNA ploidy has recently been identified as a strong prognostic factor [5–12] but it is not routinely employed in clinical practice. On the basis of the review of the literature [5–7, 9, 11] and of our results [13] supporting the strong and independent prognostic significance of DNA ploidy, since 1999 we decided to use this factor prospectively in clinical practice.
Purposes of this study were to delineate on the basis of DNA content a low-risk group that could be spared adjuvant treatment and to compare survival rate and relapse rate between patients treated before and after the introduction of DNA ploidy. Secondary, we wanted to evaluate the predictive value of traditional prognostic indicators and of DNA ploidy in stage I endometrial cancer (EC).
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material and methods |
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Two hundred and twenty-two consecutive cases of stage I endometrioid EC, referred to the Department of Obstetrics and Gynecology, San Raffaele Hospital of Milan, from 1990 to 2003 were considered for the purpose of this study.
All the patients underwent primary surgery: the operation has been established according to the age and clinical conditions of each patient. Twenty cases received vaginal hysterectomy and seven patients were treated by laparoscopic-assisted vaginal hysterectomy and bilateral salpingo-oophorectomy; in the other cases, total abdominal hysterectomy and bilateral salpingo-oophorectomy were carried out. Cytology was also obtained at the beginning of the surgical procedure.
Pelvic lymphadenectomy was carried out in 100 patients (45%): lymph node status was unknown for all other patients since they were either referred to our institution after primary surgery or randomized between pelvic lymphadenectomy and nodes sampling if grossly involved according to the ongoing randomized study [14].
All patients included in the study were affected by stage I endometrioid cancer of the endometrium.
Stage and histological grading were evaluated according to the 1988 International Federation of Gynecology and Obstetric (FIGO) classification [15].
Cytofluorimetric analysis of DNA content was carried out later on paraffin-embedded tissue for patients of both groups: this parameter represented the most important prognostic factor for postoperative management of group B. The DNA index was calculated as the ratio between the mode of the relative DNA content of G0/G1 cells of the sample and the mode of the relative DNA measurement of the diploid G0/G1 reference cells [16].
All the cases were divided into non-diploid (DNA index >1.2), near-diploid (0.8 < DNA index < 1.2) and diploid (DNA index = 1) groups; diploid and near-diploid tumors were considered together [13].
The study population is chronologically divided in two groups: first group (group A, n = 141) included patients treated from 1990 to 1998, who received AT in stage IC. Inclusion criteria for the first group were as follows: stage IC G1/2 received external RT and stage IC G3 were randomized to receive RT or chemotherapy (five consecutive courses of cisplatin 50 mg/m2, cyclophosphamide 600 mg/m2 and adriamycin 45 mg/m2 every 28 days) [17]. The radiation plan consisted of a total radiation dose of 50.4 Gy. RT was given in five fractions per week (1.8 Gy daily dose) during 5 weeks. The irradiation field encompassed the entire pelvis as follows: the high limit was tangential to the upper surface of L5, the lower limit comprehended the upper third of vagina and the lateral limits were not <2 cm outside the ileopectineal ligament.
The second group included 81 patients (group B), treated from 1999 to 2003, who were submitted to adjuvant treatment in case of either DNA index >1.2 or in stage IC G3 with unknown lymph nodal status.
In the second group (group B, n = 81), adjuvant treatment was represented by external RT or chemotherapy with paclitaxel 60 mg/mq weekly and concomitant external RT for 5 weeks, followed by three additional consolidation courses of paclitaxel 80 mg/mq administered every 21 days [18].
The follow-up included history and gynecological examination. Pap smear of the vaginal vault and complete abdominal ultrasonography were carried out every 6 months, chest radiographs were carried out once a year and computed tomography scans and blood test were done on indication. All patients were evaluated every 3 months during the first 3 years and thereafter every 6 months.
statistical analysis
Overall survival (OS) was calculated from the day of surgery to the date of death or last contact.
The t-test and chi-square analysis were used to compare, respectively, continuous and nominal variables between the two groups (group A versus group B).
Log rank and Cox proportional hazards model [19] were used to assess the effect of each variable (stage, age at time of diagnosis, degree of differentiation, DNA ploidy, lymphovascular space invasion, lymph node status and distinction group A/group B) on OS and disease-specific mortality.
Since there were few events of tumor-related deaths, only univariate analysis of prognostic factors was carried out.
Fisher's exact test was used to determine relative risk of recurrence in group B versus group A.
Log rank was used to determine the effect of prognostic factors (stage, age at time of diagnosis, degree of differentiation, DNA ploidy and lymphovascular space invasion) on recurrence risk.
Survival curves were done according to Kaplan–Meier method, including log-rank analysis.
P values <0.05 were considered significant.
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results |
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characteristics of patients
Two hundred and twenty-two patients were included in the study, of whom 141 (group A) treated from 1990 to 1998 and 81 (group B) from 1999 to 2003. Median age was 62 years. No significant difference in age [t-test, P = not significant (NS)], body mass index (chi-square test, P = NS) and performance status (chi-square test, P = NS) was found between the two groups. Median follow-up was 4.75 years, 5.7 in group A (range 4.1–10 years) and 3.75 in group B (range 2–7.75 years). All the patients were affected by endometrioid endometrial adenocarcinoma in stage I. Forty-six of 222 (20.6%) were in stage IA, 111 of 222 (50.2%) were in stage IB and 65 of 222 (29.2%) were in stage IC. According to the grading, we observed 46% of G1, 46% of G2 and 8% of G3. A diploid DNA pattern was found in 91.9% of tumor specimens and 8.1% were classified as non-diploid (Table 1). Characteristics of patients in stage IC are summarized in Table 2.
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In group A, 54.6% of patients underwent lymph node exploration, whereas in group B only 28%. This considerable difference between the two groups is due both to the participation in the randomized study on lymphadenectomy [14] and to the increased number of patients referred for postoperative decision at stage IC. As shown in Table 1, stage IC patients are, respectively, the 20.6% of cases in group A and the 44.4% in group B.
Eight patients of group B were in stage IC grade 3, of whom 5 received AT because non-diploid, 2 diploid got AT for unknown lymph node status and 1 diploid and surgically staged received no further treatment.
adjuvant treatment
In total, 110 of 141 (78%) patients of group A and 69 of 81 (85.2%) of group B were treated with surgery alone; 31 of 141 (22%) patients of group A and 12 of 81 (14.8%) of group B received adjuvant treatment. None of the patients in stage IA received postoperative therapy.
In stage IB, only three patients received AT: two of group A (major protocol violations) and one of group B. In group B, AT was performed in one patient stage IB non-diploid, in 9 patients stage IC non-diploid and in 2 patients stage IC grade 3 with unknown lymph node status.
In stage IC, the different criteria of postoperative risk assignment determined a statistically significant difference in AT rate between the two groups: 29 of 29 (100%) patients in stage IC of group A received adjuvant treatment versus 11 of 36 (30.6%) of group B (P < 0.0001) (Table 3).
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outcome
Final event, defined according to date of death or last contact, showed 204 patients still alive and free of disease, 12 dead of other causes and 6 dead of EC. No patients alive with disease were reported.
Overall recurrence rate was 9 of 222 (4%) (5 patients of group A and 4 patients of group B) with a recurrence rate of 3.5% in group A and 4.9% in group B, without any statistically significant difference. Relative risk of recurrence in group B versus group A was 1.39, with a 95% confidence interval of 0.38 to 5.04 (P = 0.73, Fisher's exact test).
Characteristics of patients who developed tumor recurrence are illustrated in Table 4.
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Fifty-six per cent (five of nine) of recurrences were non-diploid tumors at first diagnosis.
Four of five patients of group A who developed tumor recurrence had not received adjuvant treatment and received salvage treatment with complete response in two cases.
Since ploidy was introduced as a ‘decision-making’ factor, 25 of 36 (69.4%) patients in stage IC were spared adjuvant treatment with no tumor-related mortality in this group. Three of four patients of group B who developed tumor recurrence had been correctly identified as high-risk ones according to DNA ploidy and had received AT. Only one patient of group B did not receive AT because diploid developed local tumor recurrence and was successfully treated with surgery and RT at relapse.
On the other side, only one patient of group B received AT because non-diploid would not have been treated according to traditional prognostic factors and did not developed tumor recurrence.
In group A, five patients recurred of whom only one had received AT according to traditional prognostic factors; according to ploidy, two of five patients would have been identified as high risk in this small subset of patients.
The most interesting datum among these cases of recurrence is that the only three patients who are alive and free of disease after relapse and combined salvage treatment had diploid tumor at first diagnosis (Table 4).
Six of 222 patients died because of their neoplasm. In five of six cases of disease-specific deaths, DNA index was >1.2 (non-diploid).
prognostic factors analysis
Univariate analysis (log rank) showed a significant relation of OS with DNA ploidy (P = 0.003), grade of differentiation (P = 0.05) and age at time of diagnosis (Cox, P < 0.0001) (Table 5).
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At multivariate analysis (Cox) on OS, only DNA ploidy (P = 0.01) and age at time of diagnosis (P < 0.0001) resulted to be independent prognostic factors (Table 6).
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The risk of disease-specific death at univariate analysis (log rank) resulted significantly related to grade of differentiation (P = 0.0195) and DNA ploidy (P < 0.0001).
Also recurrence risk is significantly associated with DNA content: DNA ploidy resulted as the only prognostic factor related to recurrence risk (log rank, P < 0.05).
Among diploid tumors (204 of 222), only 1 of 204 (0.5%) died of EC, while among 18 patients with non-diploid tumors 33.4% tumor-related deaths were reported.
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discussion |
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TopAbstractintroductionmaterial and methodsresultsdiscussionReferences |
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Postoperative treatment decisions in EC patients are usually solely on the basis of traditional risk factor such as depth of myometrial invasion, degree of differentiation and lymphatic–vascular space invasion and their association with recurrence risk [1–4, 20].
Conventional prognostic indicators already allow for the identification of a group of patients at increased risk of recurrence and AT can be offered to these individuals.
Recently, Naumann and Coleman [21] analyzed current patterns of care for early-stage EC by the members of the Society of Gynecologic Oncologists and reported that for stage IB grade 3 and all stage IC most gynecologic oncologists recommend some type of adjuvant radiation therapy (vaginal cuff radiation, whole pelvic radiation or whole abdominal radiation).
Historically, adjuvant treatment has been in the form of whole pelvis radiation therapy to improve local control. This has not translated into improved OS [2–4]. Moreover, many patients are overtreated, with its attendant costs and morbidity. We believe that a more accurate prognostic assessment is needed to identify groups of patients who may benefit from AT.
Most authors on the basis of retrospective analysis have found tumor ploidy to be an independent prognostic indicator in EC [5–10, 13]. Terada et al. [22] reported a higher mortality in non-diploid tumors; moreover, recently Susini et al. [23] and Hogberg et al. [24] demonstrated in a prospective study the prognostic role of ploidy in EC patients.
Our results show that the independent prognostic indicators of OS are DNA ploidy and age at diagnosis.
On the basis of the review of the literature and of our experience [13], we started in 1999 a ploidy-based treatment policy in stage I endometrioid EC patients.
Before 1998 (group A), 100% of patients in stage IC received adjuvant treatment; after that date (group B), AT was administered only in case of DNA index >1.2 at cytofluorimetric analysis, independently of FIGO stage, and in stage IC grade 3 if lymph node status was unknown. From 1999 to 2003, only 30.6% of stage IC EC patients received adjuvant treatment, without any statistically significant difference in recurrence rate between the two groups. Moreover, all the three patients of group B who developed tumor recurrence and died had correctly been identified as high-risk ones, because non-diploid, and had received AT. According to ploidy, only 2 of 29 (6.9%) patients in stage IC of group A would have received AT.
With this ploidy-based treatment policy we have demonstrated that a large number of patients could be spared AT with no tumor-related deaths in this group of patients: only one patient of group B with diploid EC developed a local relapse and was successfully treated with surgery and RT. These results clearly indicate that ploidy is a useful marker in postoperative management.
When we started our study in 1999, DNA ploidy was rarely employed in clinical practice in order to identify high-risk patients. Lim et al. [12] reported that patients in stage IB-G1/G2 with non-diploid tumors treated with adjuvant RT have the same risk of relapse as untreated patients with diploid tumors. Hogberg et al. [24] used conventional prognostic indicator and DNA ploidy in order to estimate the risk of progression or death of disease and to tailor treatment in 355 FIGO stage I–II endometrioid EC patients: their results show that DNA ploidy contributes to discriminate between a low-risk and a high-risk group in association with depth of myometrial invasion and grade of differentiation.
Moreover, the use of adjuvant RT, which represents the standard adjuvant treatment for women with a high risk of local recurrence, remains controversial [2–4].
Matching sites of relapses and ploidy we found that all non-diploid patients died of EC, of whom four of five have had distant recurrences and one of five local. On the other side, three-fourths of diploid patients have had local relapses and are now alive without evidence of disease after salvage treatment. The current and other published studies [22, 24] also found a relatively lower number of local recurrences in patients with non-diploid tumors. In Table 7, we can observe that 64.3% of diploid relapses are locoregional and most of them have been treated successfully with salvage therapy, whereas non-diploid tumors in 58.3% of cases recur at distant sites and rarely can be cured after relapse. Diploid tumors can be effectively treated by salvage treatment at time of recurrence; therefore, postoperative therapy in these patients is probably unnecessary.
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In our experience, DNA index >1.2 defines a subset of more aggressive tumors that clearly require AT but external RT could be expected to fail in cases with distant progression. Thus, effective systemic treatments need to be developed.
Considering the controversial value of adjuvant RT [2, 3] and the demonstrated relative success in treating isolated pelvic relapse [25–28], we believe that our ploidy-based treatment policy could be a valid suggestion for clinical management of stage I EC patients. Randomized controlled trials are required to address this issue.
Received for publication May 25, 2007. Revision received December 20, 2007. Accepted for publication January 28, 2008.
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