Rituximab in combination with fludarabine chemotherapy in low-grade or follicular lymphoma.

PURPOSE: To evaluate the safety and efficacy of fludarabine plus rituximab in treatment-naive or relapsed patients with low-grade and/or follicular non-Hodgkin's lymphoma. PATIENTS AND METHODS: This was an open-label, single-arm, single-center phase II study enrolling 40 patients. During the first week of the study, patients received two infusions of rituximab 375 mg/m2 administered 4 days apart. Seventy-two hours after the second infusion of rituximab, patients received the first of six cycles of fludarabine chemotherapy (25 mg/m2/d for 5 days on a 28-day cycle). Single infusions of rituximab were administered 72 hours before the second, fourth, and sixth cycles of fludarabine, and two infusions of rituximab were given 4 weeks after the last cycle of fludarabine. Treatment duration was 26 weeks. RESULTS: An overall response rate of 90% (80% complete response rate) was achieved in the intent-to-treat population. Similar response rates were seen in treatment-naive and previously treated patients. The median duration of response has not been reached at 40+ months. The median follow-up time in this study is 44 months (range, 15 to 66 months). In patients positive for the 14;18 translocation in blood and/or marrow at enrollment, molecular remission was achieved in 88% of cases, with patients remaining negative for up to 4 years to date. Hematologic toxicity was manageable, and except for a 15% incidence of herpes simplex/zoster infections, infectious complications were rare. Nonhematologic toxicities were minimal. CONCLUSION: Rituximab plus fludarabine was well tolerated and associated with an excellent complete response rate, including molecular remissions, in patients with low-grade or follicular lymphoma.

Frequency of an allele for low activity of alpha-L-fucosidase in sera: possible increase in epithelial ovarian cancer patients.

Sera from a group of patients with ovarian cancer had a statistically significant deficiency of alpha-L-fucosidase activity compared with sera from healthy females or female patients with cervical or breast cancer. Mixing experiments did not identify an inhibitor of alpha-L-fucosidase activity in the sera of ovarian cancer patients. Decreased activity of alpha-L-fucosidases was not associated with stage of disease, tumor burden, histologic type, or grade of differentiation. Unlike alpha-L-fucosidase, beta-man-nosidase and beta-N-acetylglucosamindase in sera of ovarian cancer patients were not deficient in activity. Examination of population data of healthy females and of pedigrees of ovarian cancer patients suggested that the quantitative activity alpha-L-fucosidase in serum was genetically determined. Of 60 healthy females, 4 had low enzyme activity (less than 100 U alpha-L-fucosidase/ml serum), 26 had intermediate activity (100-274 U alpha-L-fucosidase/ml), and 30 had high activity (275 U/ml), whereas of 44 ovarian cancer patients, 11 had low, 29 had intermediate, and 4 had high activity. Application of the Hardy-Weinberg law to these data revealed that low enzyme activity in sera was three times more prevalent in the ovarian cancer group, the allele for this low enzyme activity being two times more common. These observations suggested that deficiency of alpha-L-fucosidase activity in sera of females may be a hereditary condition associated with increased risk for development of ovarian cancer.

Tumor progression of murine epidermal cells after treatment in vitro with 12-O-tetradecanoylphorbol-13-acetate or retinoic acid.

Tumor-promoting or antipromoting agents potentially may act directly on initiated squamous epithelial cells or indirectly through effects on normal keratinocytes or immune cells. The purpose of this study was to examine direct effects by comparing in vitro and in vivo treatment of initiated cell populations with 12-O-tetradecanoylphorbol-13-acetate (TPA) or retinoic acid. Keratinocytes were initiated by treatment in vitro with 7,12-dimethylbenz[alpha]anthracene. Replicate cultures of a cloned initiated cell line were exposed to TPA or retinoic acid with acetone as control. After an equivalent number of population doublings, cultured cell sheets were transplanted as skin grafts to athymic nude mice. Replicate grafts from each in vitro treatment group were then treated with TPA or retinoic acid for 8 months. Promotion was quantified by tumor incidence (graft sites with tumor per total sites) and by tumor growth rate. The findings were as follows: (a) TPA increased tumor incidence whether it was applied in vitro or in vivo; (b) TPA in vitro favored more progressive tumors than TPA in vivo; (c) stages of malignant progression from cloned keratinocytes treated in vitro were histologically identical to those following treatment of skin in vivo, including papilloma, dysplastic invasive papilloma, squamous cell carcinoma, and metastasis to lymph node and lung; (d) retinoic acid treatment in vivo reduced tumor incidence and tumor growth rate in initiated cells previously exposed to TPA but not in cells previously exposed to retinoic acid. The results indicated the following: (a) direct effects of TPA on initiated keratinocyte populations were a significant component of tumor promotion; (b) factors in vivo modified the TPA response toward less progressive growth; and (c) the effect of retinoic acid was modulated by prior treatment history.

Expression of c-mpl mRNA, the receptor for thrombopoietin, in acute myeloid leukemia blasts identifies a group of patients with poor response to intensive chemotherapy.

PURPOSE: c-mpl, the human homolog of v-mpl, is the receptor for thrombopoietin. Given that c-mpl expression carries an adverse prognosis in myelodysplastic syndrome and given the prognostic significance of expression of other growth factor receptors in other diseases, we attempted to determine whether c-mp/mRNA expression is a prognostic factor in acute myeloid leukemia (AML). PATIENTS AND METHODS: We analyzed bone marrow samples from 45 newly diagnosed AML patients by reverse-transcription polymerase chain reaction. RESULTS: Samples from 27 patients (60%) expressed c-mpl mRNA (c-mpl+); their clinical and laboratory features were compared with those of the 18 patients without detectable levels of c-mpl(c-mpl-). No significant differences in age, sex, leukocyte count, French-American-British subtype, or karyotype group were found. c-mpl+ patients more commonly had secondary AML (41% v 11%; P = .046) and more commonly expressed CD34 (67% v 12%; P = .0004). There was no significant difference in complete remission (CR) rate. However, c-mpl+ patients had shorter CR durations (P = .008; median, 6.0 v > 17.0 months). This was true when only de novo AML patients were considered and when controlling for age, cytogenetics, or CD34 expression. There was a trend toward shorter survival in c-mpl+ patients (P = .058; median, 7.8 v 9.0 months). CONCLUSION: These data suggest that c-mpl expression is an adverse prognostic factor for treatment outcome in adult AML that must be considered in the analysis of clinical studies using thrombopoietin in AML.

HLA-DR antigen-negative acute myeloid leukemia.

Human leukocyte antigen (HLA) Class II antigens are variably expressed on acute myeloid leukemia (AML) blasts. The biological and clinical significance of HLA Class II antigen expression by AML cells is not known. Therefore, we sought to characterize cases of AML without detectable HLA-DR expression. Samples from 248 consecutive adult AML patients were immunophenotyped by multiparameter flow cytometry at diagnosis. HLA-DR antigens were not detected on AML cells from 43 patients, including 20 with acute promyelocytic leukemia (APL), and 23 with other subtypes of AML. All APL cases had t(15;17), but there were no characteristic chromosome abnormalities in non-APL cases. No direct expression of other antigens was identified in HLA-DR-negative APL and non-APL cases. Interestingly, cells from three HLA-DR-negative non-APL patients had similar morphology to that of the hypogranular variant of APL. This morphology, however, was not present in any HLA-DR-positive AML cases. Treatment response was similar in the 23 HLA-DR-negative non-APL and the 205 HLA-DR-positive patients. Finally, relapse was infrequently associated with changes in HLA-DR antigen expression, as the HLA-DR antigen was lost at relapse in only 4% of HLA-DR-positive cases, and was gained at relapse in only 17% of HLA-DR-negative cases. We conclude that HLA-DR-negative AML includes approximately equal numbers of APL and non-APL cases, and that the morphology of HLA-DR-negative non-APL cases can mimic the hypogranular variant of APL. The diagnosis of APL cannot be based on morphology and lack of HLA-DR antigen expression; rather, it requires cytogenetic or molecular confirmation.

Cathepsin D and dynamic magnetic resonance imaging gadolinium enhancement in malignant and benign breast lesions.

Our purpose was to determine whether the expression of cathepsin D, a proteolytic enzyme implicated in basement membrane degradation, is associated with dynamic magnetic resonance imaging (MRI) enhancement of breast lesions. Forty-five patients with 48 breast lesions underwent gadolinium-enhanced spoiled gradient recalled echo MRI followed by excisional biopsy and cathepsin D staining and semiquantitative measurement in the lesions. There was no significant difference in cathepsin D staining of 25 malignant and 23 benign breast lesions. A significant association was seen between high cathepsin D staining and positive axillary lymph nodes in invasive carcinomas. Nine of nine (100%) node-positive carcinomas had high cathepsin D, as compared to three of seven (43%) node-negative carcinomas (P = 0.02). No significant associations were observed between cathepsin D staining and MRI enhancement amplitude, rate, or washout. Cathepsin D has no effect upon MRI gadolinium enhancement of malignant and benign breast lesions but is associated with positive axillary lymph nodes in invasive carcinomas.

Daily subcutaneous injection of low-dose interleukin 2 expands natural killer cells in vivo without significant toxicity.

We aimed to determine the toxicity and immunological effects of daily s.c. administered low-dose interleukin (IL) 2. Adult cancer patients received a single daily s.c. injection of IL-2 as outpatients for 90 consecutive days. Cohorts of four to nine patients were treated at escalating IL-2 dose levels until the maximum tolerated dose (MTD) was defined. Peripheral blood mononuclear cell phenotyping, IL-2 serum levels, and the presence of anti-IL-2 antibodies were investigated. Thirty-eight patients were treated at seven IL-2 dose levels ranging from 0.4 to 1.75 million International Units (mIU)/m2 daily. The MTD was 1.25 mIU/m2, with constitutional side effects, vomiting, and hyperglycemia dose limiting. Severe toxicity did not occur at or below the MTD, although mild local skin reaction and mild constitutional side effects were common. Objective tumor regressions were not observed during this Phase I trial. Low-dose IL-2 resulted in natural killer (NK) cell (CD3(-) CD56(+)) expansion at all dose levels. This effect was dose dependent (P < 0.01), ranging from a 154 to 530% increase over baseline. Peak NK levels were achieved at 6-8 weeks and sustained through 12 weeks of therapy. As predicted by in vitro studies of IL-2 receptor structure-activity relationships, the subset of NK cells that constitutively express high-affinity IL-2 receptors (CD3(-)CD56(bright+)) showed more profound dose-dependent expansion, with increases ranging from 368 to 2763% (P = 0.015). NK expansion occurred at peak IL-2 levels <10 pM (2.3 IU/ml). Three patients developed nonneutralizing anti-IL-2 antibodies. Thus, we concluded that selective expansion of NK cells may be achieved in vivo with daily s.c. injections of low-dose IL-2 with minimal toxicity.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) priming of high-dose etoposide and cyclophosphamide: a pilot trial.

Given the limitations of bone marrow transplantation (BMT), alternative approaches to deliver dose-intensive regimens without stem cell support are needed. Administration of hematopoietic growth factors before high-dose chemotherapy (priming) may reduce myelosuppression directly, delaying the onset of neutropenia by expanding the mature neutrophil compartment, and shortening the duration of neutropenia by expanding progenitor cell mass. Priming may also render progenitor populations mitotically quiescent after growth factors are withdrawn, thereby making them less sensitive to the cytotoxic effects of chemotherapy. It is also possible, however, that growth factor priming may worsen aplasia when used with dose-intensive regimens by either depleting early progenitor pools or recruiting progenitor populations into cycle. To determine the safety and hematopoietic efficacy of growth factor priming, 13 patients with hematologic malignancy or breast cancer were treated with granulocyte-macrophage colony-stimulating factor (GM-CSF) (250 micrograms/m2 twice daily subcutaneously) until the white blood cell (WBC) count reached either a plateau or 100,000 cells/microL. Forty-eight hours after the last dose of GM-CSF, chemotherapy was begun using high-dose etoposide and cyclophosphamide. All patients received GM-CSF after chemotherapy. Two patients were withdrawn during GM-CSF priming because they developed urticarial rashes. The maximum median increases in WBC and absolute neutrophil count (ANC) during GM-CSF priming were 7.1- and 4.4-fold, respectively. Only one patient achieved the original target WBC of 100,000/microL. The kinetics of leukocyte expansion were slow; a median of 13 days was needed to reach the maximum WBC. Furthermore, much of the leukocyte expansion was caused by an increase in eosinophils, which would not be expected to accelerate hematopoietic recovery. GM-CSF priming did not appear to have a significant impact on hematopoietic recovery after high-dose etoposide and cyclophosphamide, as there was no significant difference in 1) recovery to an ANC > 500/microL compared to a historical control group that received no growth factor (median of 29 and 30 days, respectively; p = 0.4), 2) number of days with an ANC < 500/microL (median of 19 and 20 days, respectively; p = 0.11), and 3) number of days to an untransfused platelet count > or = 50,000/microL (median 36 and 32 days, respectively; p = 0.23). The failure of GM-CSF priming may be a result of its modest stimulation of hematopoiesis or the expansion of a committed progenitor cell population that is exquisitely sensitive to this regimen.

Adjuvant chemotherapy with a nitrosourea-based protocol in advanced malignant melanoma.

173 patients with regional lymphatic metastases (n = 139) or distant disease (n = 34) were prospectively randomised, following resection of all clinically detectable tumour, to observation (n = 88) or adjuvant chemotherapy (n = 85). The treatment group received 1, 3-bis(2-chloroethyl)-1-nitrosourea (BCNU) 80 mg/m2 intravenously (i.v.) every 4 weeks, and actinomycin-D 10 micrograms/kg, vincristine 1.0 mg/m2 i.v. every 2 weeks for 6 months. The disease-free survival curves between the two groups were significantly different (P = 0.03). The estimated 5-year disease-free survival rate for the observation group was 9% and for the treatment group 29%. However, the overall survival curves were not significantly different for the two groups. Nitrosoureas may have a weak effect as adjuvant treatment in malignant melanoma.

Subungual melanoma: an eighteen-year review.

BACKGROUND: Subungual melanoma is a rare lesion comprising 1% to 3% of all melanoma cases. METHODS: Records of twenty-two patients with subungual melanoma treated at Roswell Park Cancer Institute during the period September 1971 to September 1989 were reviewed in a retrospective manner. Most common sites of involvement were the great toe on the foot (n = 7), the thumb (n = 4), and the index (n = 3) and ring fingers (n = 3) on the hand. Common signs included pigmentation of the nail bed, nail loss, and nail destruction. RESULTS: Thickness of the lesion could be determined in 10 patients. All four patients with lesions 1.0 mm and thinner at the time of biopsy were alive and disease free at 19, 20, 55, and 78 months, whereas three of six patients with lesions thicker than 1.0 mm were dead at 15, 51, and 56 months. Patients with ulcerated lesions had an estimated 5-year survival rate of 39% as compared with 80% for the group without ulceration. Seven patients underwent finger amputations distal to the metacarpophalangeal joint, and none experienced local recurrence. Four amputations were just proximal to the distal interphalangeal joint, and three were just proximal to the proximal interphalangeal joint. One of these patients died of metastatic melanoma at 56 months, and the other six were alive and disease free at 13, 19, 20, 32, 72, and 78 months from the time of diagnosis. CONCLUSIONS: More distal amputations of subungual melanomas of the hand preserve function and do not compromise survival or local control.

Malignant peritoneal cytology as prognostic indicator in stage I endometrial cancer.

The prognostic significance of malignant peritoneal cytology was evaluated in 93 patients with stage I endometrial cancer seen at Roswell Park Memorial Institute. Eighty-three patients (89%) had negative cytologic samples and ten (11%) had positive cytology for neoplastic cells. All patients were followed for a minimum of ten years or until dead from cancer or intercurrent disease. No patient received treatment for positive cytology. There was one recurrence in the patients with positive cytology (10%), and six recurrences in the negative group (7%). The actuarial survival rate at five and ten years for patients with negative cytology was 93.9 and 92.5%, respectively. For patients with positive cytology, the survival was 87.5% at both time intervals. No significant difference was found between the groups. Malignant peritoneal cytology does not seem to be a prognostic indicator in stage I endometrial cancer.

Melphalan chemotherapy in advanced ovarian carcinoma.

One hundred and eleven consecutive women with FIGO Stages III and IV ovarian adenocarcinoma were treated with melphalan as their initial chemotherapy. The response rate was 19.8% with 10.8% having a complete response. There was a statistically significant improvement in response in those women with no prior radiation therapy. Moreover, there was a statistically significant improvement in median survival in those patients achieving a complete response to melphalan as compared to those with a partial response, with no change or progression of their malignancy. A review of the results of maximal surgery and combination chemotherapy is presented as a plan of therapy to improve upon the results of melphalan chemotherapy in women with advanced ovarian carcinoma.

A prospective trail comparing hysterectomy, hysterectomy plus vaginal radium, and uterine radium plus hysterectomy in stage I endometrial carcinoma.

From 1958 to 1967, a prospective randomized trial was conducted in 189 women with stage I, group I endometrial adenocarcinoma, comparing treatment by hysterectomy alone, preoperative uterine radium followed by hysterectomy, and hysterectomy and postoperative vaginal radium. All women have been followed for a minimum of 10 years. The actual survival rate at 5 years for all patients was 94.5% and at 10 years, 92.6%, with no statistical significance among the 3 treatment groups. Ther was also no statistical significance in survival rate in relation to size of uterine or myometrial invasion. There was a statistically significant difference in survival between grade I and grade III lesions (P less than 0.01) and between grade II and grade III lesions (P less than 0.05).

Paraaortic lymph node evaluation in stage I endometrial carcinoma.

Of 41 women with FIGO stage I endometrial adenocarcinoma who underwent staging paraaortic lymphadenectomy and paraaortic node biopsy, 6 (14.6%) had metastasis to the paraaortic lymph nodes. None of the 11 patients with grade 1 carcinoma had paraaortic node metastasis; 13.6% of grade 2 carcinomas and 37.5% of grade 3 carcinomas were associated with paraaortic node metastasis. None of the 8 patients with tumor limited to the endometrium had paraaortic metastasis, and only 4.5% of the patients with superficial myometrial invasion had metastasis to the paraaortic lymph nodes. However, this increased to 45.5% for tumors deeply invading the myometrium. Of the patients with paraaortic node metastasis, 83.3% had either grade 3 tumors or deep myometrial invasion. Only 1 patient in the study with paraaortic node metastasis did not have either a grade 3 carcinoma or a tumor deeply invading the myometrium. Because of the high incidence of paraaortic node metastasis with grade 3 tumors or deep myometrial invasion, surgical staging by paraaortic lymphadenectomy or lymph node biopsy is recommended at the time of primary surgery for early endometrial adenocarcinoma.

Uterine endolymphatic stromal myosis: a collaborative study.

Fifty-two cases of the rare entity, uterine endolymphatic stromal myosis, were evaluated in a collaborative study by gynecologic oncologists trained at the M. D. Anderson Tumor Institute. Fifty percent developed recurrent disease subsequent to initial surgical therapy. Of the surgical stage I cases, 47% developed pelvic recurrences, and 9% developed distant recurrences only after initial therapy. The five- and ten-year life-table survival of surgical stages I to IV were 88% for stage I, 66% for stage II, 100% for stage III, and 75% for stage IV. These long-term survival rates were due in part to the hormonal sensitivity of the recurrent tumors. Because of the high recurrence rate after initial therapy, a suggested plan of therapy is presented for patients with uterine endolymphatic stromal myosis.

99mTc-IMMU-4 monoclonal antibody scan in colorectal cancer. A prospective study.

A blinded prospective study of 34 patients with colorectal adenocarcinoma using the Fab' fragment of the anticarcinoembryonic antigen monoclonal antibody type IMMU-4 labeled with technetium 99m was conducted to compare, on a lesion-by-lesion basis, the findings of radioimmunoscintigraphy, preoperative computed tomography, and exploratory celiotomy. Of 115 lesions detected at surgery, 113 were adenocarcinoma. Radioimmunoscintigraphy detected 59 lesions and computed tomography detected 62; both studies combined detected 72. Twenty-nine (54%) lesions missed by radioimmunoscintigraphy and 24 (45%) missed by computed tomography were 1 cm or smaller. When both studies were combined, the sensitivities were 90%, 24%, and 42%, and the specificities were 52%, 86%, and 61% for hepatic, extrahepatic intra-abdominal, and pelvic lesions, respectively. In 10 patients, additional information obtained with the radioimmunoscintigram could have altered the treatment of these patients. In this study, radioimmunodetection scan was complementary to computed tomographic scan in the examination of patients with colorectal carcinoma.

Expression and function of the megakaryocyte growth and development factor receptor in acute myeloid leukemia blasts.

The receptor for megakaryocyte growth and development factor (MGDF), also known as thrombopoietin, has recently been cloned. MGDF stimulates platelet production and maturation both in vitro and in vivo. MGDF may thus have a role in attenuating the thrombocytopenia associated with acute myeloid leukemia (AML) and its therapy. However, there is concern that MGDF might induce AML blast proliferation and thereby increase the risk of treatment failure. To address this concern, we studied the expression of c-mpl mRNA and c-Mpl protein by blasts from AML patients. In addition we examined the in vitro effect of MGDF as well as the combined effect of MGDF and granulocyte colony-stimulating factor (G-CSF) or stem cell factor (SCF) on leukemic blast proliferation, recruitment into S-phase, induction of programmed cell death and activation of signal transducers and activators of transcription (STAT) proteins. Our results demonstrate that blasts from a substantial proportion of cases of AML express the receptor at either the mRNA or protein level. Moreover, the function of the MGDF receptor was demonstrated by activation of STAT proteins following exposure to MGDF. Nevertheless, blast proliferation in response to MGDF was rare, and the proliferative effect of MGDF was less than that of G-CSF or SCF. Furthermore, MGDF did not prevent programmed cell death induced by cytarabine. Finally, there appeared to be no correlation between receptor expression by AML blasts and functional response to MGDF. Based on these data, it would appear that clinical trials of MGDF may be undertaken safely in patients with AML.

Patterns of occurrence of second primary non-mammary malignancies in breast cancer patients: results from 1382 consecutive autopsies.

An autopsy series on the patterns of occurrence of second primary non-mammary malignancies (SPNM) in breast cancer patients is presented. SPNM occurred in 11.4% of breast cancer patients at a mean interval of 83.9 months. Seventy-five per cent of them occurred by the first decade following breast cancer. The most common system of SPNM occurrence was the female genital system, followed by the gastrointestinal system. The single organs most commonly involved were the colon and rectum, ovary and uterine cervix. There was no evident association between administration of radiotherapy or chemotherapy for the breast cancer and the risk for SPNM development except in the case of post-radiation sarcomas at or near the site of post-mastectomy radiotherapy. Death was caused by the breast cancer in 28.7% of patients and by the SPNM in 53.5%. In 10.6% of the cases the SPNM was clinically interpreted as metastatic breast cancer until autopsy.

Factors affecting outcome in locally advanced breast cancer.

Patients presenting with locally advanced breast cancer (LABC) constitute a diverse group for which a variety of treatment modalities have been instituted. To assess which factors have a direct impact on outcome, we reviewed the medical records of 104 patients diagnosed with stage IIIA, stage IIIB and T3N0M0 breast carcinoma. When considered individually (univariate analysis), clinical stage, pathological stage, oestrogen receptor status and type of therapy were significant predictors for disease-free survival (DFS) and overall survival (OS). However, in a multivariate analysis, only clinical stage was a significant predictor for both DFS and OS, while ER status was a significant predictor for OS. There was a high degree of correlation between clinical and pathological staging. Nearly two-thirds of the patients developed a recurrence by 5 years. Loco-regional recurrence was the site of first recurrence in one-third of the patients by 5 years. The prognosis for patients presenting with LABC is poor, and they should be treated aggressively with loco-regional and systemic multimodality therapy. Although groups of patients with improved outcome could be identified by clinical or pathological staging, no group demonstrated an outcome good enough to be spared from multimodality therapy.

Surgery for disseminated abdominal sarcoma.

Seventy-two consecutive patients with disseminated soft tissue sarcoma in the abdomen were prospectively placed in a program of debulking surgery. The tumor was completely resectable in 64% of the patients. Following the first exploration, the median survival was 23 months for those with resection of metastases and 9 months for those without resection (p less than or equal to 0.01); the former group had a survival rate of 28% at 3 years, 18% at 4 years, and 4% at 5 years (44%, 37%, and 10%, respectively, for low-grade sarcomas, i.e., grade I or II sarcomas), whereas in the latter group, none survived for 3 years. In the group with resection, patients with grade III tumors had a median survival longer by 6 months, and those with low-grade tumors by 28 months (p less than or equal to 0.001), over the respective median survival of patients with unresectable tumors. Metastasectomy appeared to prolong survival in all patients and significantly so in patients with low-grade tumors and those with long disease-free intervals.