High S-phase Fraction Research Articles

Proliferative activity of breast cancers increases in the course of genetic evolution as defined by cytogenetic analysis

The prognostic value of proliferative activity and its relationship with steroid hormone receptors and histopathological grade have been demonstrated for breast cancers. However, nothing is known about the underlying mechanisms. In order to understand the chronology of the appearance of increased proliferative activities, we used a series of 760 consecutive breast cancers for which we had obtained S-phase fractions (SPFs) by DNA flow cytometry. When the absolute difference from a DNA index of 1.00 was compared to SPFs, a significant positive correlation was obtained (r = 0.39, p < 0.0001), indicating that the probability of observing a high SPF increases when tumors progressively deviate from diploidy. A highly significant correlation was observed for the hyperploid group when hypertetraploid tumors were excluded, as the SPFs increased progressively as the DNA indices decreased from 2.00 to 1.30. This observation suggested a relationship with the evolution of chromosomal abnormalities as determined by cytogenetic analysis. Indeed, in a subset of 52 cases for which sufficient metaphases were available, there was a highly significant correlation between the SPF values and the proportion of rearranged chromosomes in the tumor cells (r = 0.60, p < 0.0001). When SPFs were separated into low or high using the median value (4.5%), a correlation also existed with the genetic evolution, since they increased from diploidy to hypodiploidy and then, after endoreduplication, from tetraploidy towards triploidy, as determined by the chromosome counts. Our results substantiate the relationship between proliferative activity and steroid hormone receptors which follow the same model.(ABSTRACT TRUNCATED AT 250 WORDS)

Proliferative activity and malignancy in human gastric cancers. Significance of the proliferation rate and its clinical application

The authors sought useful indicators for predicting the proliferative activity of human gastric cancer and attempted to evaluate its clinical significance. One hundred seventy-two patients with gastric cancer were entered in this study. All patients received bromodeoxyuridine at 200 to 1000 mg/body before laparotomy. Cell kinetics studies using the migration chase method were done for 56 patients, and the DNA synthesis time (Ts) was found to be prolonged in tumors, especially in aneuploid tumors, compared with normal mucosae. Ts correlated with bromodeoxyuridine (BrdUrd) labeling indices (LI) (r = 0.453, P less than 0.0005) and DNA indices (DI) (r = 0.534, P less than 0.0005). Thus, the DNA synthesis time was significantly prolonged in the tumors having a high S-phase fraction or DNA aneuploidy. The result of multivariate analysis indicated that LI/DI was the most potent indicator for predicting the proliferation rate (PR), which was calculated by the formula LI/Ts, and correlated significantly with PR (r = 0.863, P less than 0.0001). As was clear from the result of Cox's proportional hazard model, the predicted proliferation rate (pPR) was the most notable factor for the prognosis because pPR correlated clinically with metastasis, such as that to liver and lymph nodes. The patients with a high pPR (greater than 10%) had a worse prognosis (4-year survival rate: 16.3%) than did those with a low value (less than 10%) (4-year survival rate: 85.1%). In vitro pPR obtained by in vitro BrdUrd labeling of the specimens obtained at biopsy correlated significantly with the in vivo pPR (r = 0.960, P less than 0.0001). The authors concluded that the proliferation rate was the most important factor in judging the malignancy of human gastric cancers and that this rate should be most helpful in determining the treatment and evaluating the prognosis of individual patients.

Sequential cytopunctures during preoperative chemotherapy for primary breast carcinoma. II. DNA flow cytometry changes during chemotherapy, tumor regression, and short-term follow-up

Between May 1986 and May 1987, 35 primary noninflammatory breast carcinomas (T3N0-N1M0) were studied by means of DNA flow cytometry (FCM-DNA) before and after each of three courses of preoperative chemotherapy (doxorubicin, vincristine, cyclophosphamide, methotrexate, and 5-fluorouracil) to assess initial nuclear DNA content, initial S-phase fraction (SPF), and the impact of chemotherapy on these parameters. Correlations were sought with objective regression and short-term follow-up. Four sequential cytopunctures were performed for cytologic examination and FCM-DNA analyses. Ten tumors were diploid and 25 aneuploid. No significant changes in FCM-DNA parameters during chemotherapy were observed in diploid tumors, and no regression was seen in nine of the ten cases. Among the 25 aneuploid tumors, 10 showed changes in DNA content and/or kinetic parameters. A significant correlation was observed between objective regression and initial FCM-DNA content (P = 0.008), initial SPF (P = 0.004), and changes in FCM-DNA patterns observed during chemotherapy (P = 0.00005). During the follow-up period (range, 27 to 41 months), 13 patients had relapses. Patients with aneuploid tumors were more likely to have relapses (n = 11) than patients with diploid tumors (n = 2), and patients with high SPF were more likely to have relapses than patients with low SPF, but the differences were not significant. Similarly, changes in FCM-DNA parameters were observed more often in patients who had relapses, but, again, the difference was not significant. In 5 of the 13 patients who had relapses, FCM-DNA analyses were performed on cytopunctures of the recurrences: patterns were identical to those observed before treatment even when the primary tumor regressed or showed changes in FCM-DNA parameters during chemotherapy.

DNA ploidy pattern and S-phase characteristics of metastatic melanoma

Samples of 130 metastatic melanomas from 92 patients were analyzed by DNA flow cytometry. DNA aneuploidy was observed in 67% of the patients. DNA indices were evenly distributed from 0.6 to 2.6 Tumors originating from primary lesions in the lower extremities were more frequently DNA aneuploid than those of other sites. S-phase fraction (SPF) was evaluable from 73 tumors. DNA aneuploid tumors had a significantly higher SPF than diploid tumors, and females had a higher SPF than males. Furthermore, distant metastases had a higher SPF than metastases in regional lymph nodes and in transit metastases, probably indicating a higher growth potential in metastases spreading to distant sites.

Ras p21 expression in relation to DNA ploidy, S-phase fraction and prognosis in colorectal adenocarcinoma

ras p21 expression, as indicated by the monoclonal antibody ras 11, was estimated using immunohistochemistry on 69 primary colorectal adenocarcinomas. Also, DNA ploidy and S-phase fraction (SPF) were analysed with flow cytometry. Positive staining for ras 11 tended to be more common in DNA non-diploid tumours (P = 0.11), but was significantly correlated with high SPF (P = 0.038). Positive ras 11 staining, Dukes' stage, DNA ploidy and SPF were related to the recurrence-free interval of patients with Dukes' A-C tumours (P = 0.0014, P = 0.023, P = 0.035 and P = 0.040, respectively). ras 11 staining was a prognostic factor independent of both Dukes' stage and DNA ploidy (P = 0.011). The results indicate that pan ras p21 expression is associated with proliferative activity and has an independent prognostic value in colorectal adenocarcinoma.

Prognostic value of flow cytophotometric DNA content analysis in single treatment stage IB-IIA squamous cell carcinoma of the cervix

DNA content was measured flow cytometrically in archival tissue from 65 single-treatment stage IB and IIA squamous cell carcinomas of the cervix with at least 5 years of clinical followup. Thirty-five cases were treated exclusively by hysterectomy and thirty exclusively by radiation therapy. Tumors were categorized into four groups on the basis of DNA content and cell cycle distribution. DNA content was measured relative to the position of the first resolvable cell peak. G2/M and S-phase fractions were estimated as percentage of cells with DNA contents greater than or equal to relative position 1.70 and percentage of cells with relative positions between 1.20 and 1.70, respectively. The 40 tumors characterized as either aneuploid or nondemonstrably aneuploid with high S-phase fraction estimate had a 5-year recurrence rate significantly higher than that of the 25 tumors categorized as tetraploid or nondemonstrably aneuploid with low S-phase fraction estimate (52 and 4%, respectively; χ 2 = 15.8, P < 0.001). Similar results were found when radiation and surgically treated tumors were considered independently ( χ 2 = 7.95, P < 0.005 and χ 2 = 5.7, P < 0.025, respectively). These data suggest that an increased 5-year recurrence rate is associated with both abnormal DNA content and elevated S-phase fraction in stage IB–IIA squamous cell carcinoma of the cervix, and that this relationship is largely independent of treatment method.

DNA flow cytometric analysis of primary operable breast cancer. Relation of ploidy and S-Phase fraction to outcome of patients in NSABP B-04

Between 1971 and 1974, 1665 women with primary operable breast cancer were randomized into a National Surgical Adjuvant Breast and Bowel Project (NSABP) trial (B-04) conducted to evaluate the effectiveness of several different regimens of surgical and radiation therapy. No systemic therapy was given. Cells from archival paraffin-embedded tumor tissue taken from 398 patients were analyzed for ploidy and S-phase fraction (SPF) using flow cytometry. Characteristics and outcome of patients with satisfactory DNA histograms were comparable to those from whom no satisfactory cytometric studies were available. In patients with diploid tumors (43%), the mean SPF was 3.4% +/- 2.3%; in the aneuploid population (57%), the SPF was 7.9% +/- 6.3%. Only 29.9% +/- 17.3% of cells in aneuploid tumors were aneuploid. Diploid tumors were more likely than aneuploid tumors to be of good nuclear grade (P less than 0.001) and smaller size (P equals 0.03). More tumors with high SPF were of poor nuclear grade than were tumors with low SPF (P equals 0.002). No significant difference in 10-year disease-free survival (P equals 0.3) or survival (P equals 0.1) was found between women with diploid or aneuploid tumors. Patients with low SPF tumors had a 13% better disease-free survival (P equals 0.0006) than those with a high SPF and a 14% better survival (P equals 0.007) at 10 years than patients with high SPF tumors. After adjustment for clinical tumor size, the difference in both disease-free survival and survival between patients with high and low SPF tumors was only 10% (P equals 0.04 and 0.08, respectively). Although SPF was found to be of independent prognostic significance for disease-free survival and marginal significance for survival, it did not detect patients with such a good prognosis as to preclude their receiving chemotherapy. The overall survival of patients with low SPF was only 53% at 10 years. These findings and those of others indicate that additional studies are necessary before tumor ploidy and SPF can be used to select patients who should or should not receive systemic therapy.

Flow cytometric analysis of DNA ploidy and S-phase fraction from prostatic carcinomas: implications for prognosis and response to endocrine therapy

We analysed ploidy and S-phase fraction (SPF) from 78 paraffin-embedded primary prostatic carcinomas by DNA flow cytometry. DNA aneuploidy and above median (4.2%) SPF were both associated with high tumour grade, large size of prostate and presence of distant metastases. Both aneuploidy and high SPF (greater than 4.2%) indicated short 10-year progression-free (P = 0.01 for ploidy and P = 0.0002 for SPF), overall (P = 0.004 and P less than 0.0001) as well as prostate cancer survival (P = 0.002 and P less than 0.0001). Ten-year overall survival rate was 45% in cases with SPF below 4.2% and 0% in those with higher values, whereas the corresponding prostate cancer-specific survival rates were 80% and 11%, respectively. None of the seven tumours with SPF above 12% showed an objective response to endocrine therapy, whereas 26/49 (52%) of those with lower SPF values responded (P = 0.01). DNA ploidy, tumour grade, T-stage or M-stage did not significantly correlate with endocrine responsiveness. SPF was also the best predictor of progression free survival in patients treated hormonally. In conclusion, detection of high SPF in prostate cancer may indicate lack of hormonal responsiveness and poor prognosis.

Natural history of human breast cancer: Recent data and clinical implications

This study of the natural history of human breast cancer was based on the analysis of a series of 3000 patients treated by radical mastectomy at a single institution (Institut Gustave Roussy) at a time when adjuvant chemotherapy was not prescribed. The follow-up of the patients ranged from 15 to 30 years; for each patient the tumor size, the number of involved axillary nodes, and the histological grade were prospectively registered. A highly significant correlation was found between tumor size and the probability of distant metastatic dissemination. The distribution of tumor sizes at metastatic spread was log-normal with a median diameter equal to 3.5 cm. The patients were subdivided into 3 groups according to the histological grade. In each subgroup there was a significant correlation between tumor size and the probability of distant spread; the distributions were log-normal and the median size was markedly larger for grade 1 tumors. Moreover the proportion of grade 1 tumors was higher in small tumors than in large ones while the reverse was observed for grade 3 tumors; these data suggest that during their growth tumors progress towards higher grades. One of the chief fundamental characteristics of a tumor seems to be its propensity for axillary node invasion. The orderly pattern of nodal involvement makes it possible to calculate the tumor size at invasion of the first axillary node in each subset of patients. A strong and highly significant correlation exists between the size of the tumor at initiation of distant metastasis and at invasion of the first lymph node. However the capacity for lymphatic spread is, on average, acquired much earlier than the capacity for metastatic spread. With a simple model based on these data it was possible to compute the proportion of patients with occult metastases as a function of tumor size, histological grade, and number of involved axillary nodes. Early invasion of axillary nodes is associated with a rapid growth rate of the primary tumor (or a high S-phase fraction). However each of these variables has an independent prognostic significance; the S-phase fraction appears as one of the strongest prognostic indicators. A model of tumor growth was used to assess the impact of screening procedures on the proportion of patients with distant metastases. The predictions of the model are consistent with the results of the screening programs.(ABSTRACT TRUNCATED AT 400 WORDS)

Progression and survival in transitional cell bladder cancer: a comparison of established prognostic factors, S-phase fraction and DNA ploidy

DNA flow cytometric (FCM) data, histological features and clinical stage of bladder tumours in 222 patients were related to outcome during a mean follow-up of 10 years. Aneuploidy was detected in 82 (37%) of tumours and 140 (63%) were diploid. Intratumour heterogenity of DNA ploidy was found in 27% of 30 cases. Aneuploidy and high S-phase fraction (SPF) were related to clinical stage, histological grade and papillarity ( P < 0.0001). Aneuploidy ( P < 0.0001) and high SPF ( P < 0.0001) predicted metastasis to pelvic lymph-nodes and to distant sites. T category ( P < 0.0001), SPF ( P < 0.0001), histological grade ( P < 0.0001), papillarity ( P = 0.0021), DNA aneuploidy ( P = 0.0094) and G2 fraction ( P = 0.0340) predicted cancer-related survival. Multivariate analysis showed DNA aneuploidy as the most important predictor of progression in T category ( P = 0.0003) and T category was the most important predictor of lymph-node involvement ( P = 0.0083) and metastasis ( P = 0.0015), followed by FCM parameters. In Ta-T1 tumours SPF predicted progression independently ( P = 0.0153). FCM offers more accurate prognostic information in Ta-T1 tumours than conventional methods. In invasive tumours, FCM offers quantitative prognostic information in terms of pelvic lymph-node metastasis and metastasis to distant sites.

Proliferation and DNA ploidy in malignant breast tumors in relation to early oral contraceptive use and early abortions

In 175 premenopausal breast cancer patients, a history of oral contraceptive (OC) use before 20 years of age was significantly associated with higher tumor cell proliferative activity, as indicated by a higher S-phase fraction (SPF), and a higher fraction of DNA aneuploid tumors, compared with later or never users (P = 0.05 and p = 0.01, respectively). The higher SPF among early OC users was apparent in patients with aneuploid tumors but not in patients with euploid tumors. Abortions (spontaneous or induced) before the first full-term pregnancy also were associated with a higher SPF compared with other young patients with breast cancer (P = 0.03). Adjusting for parity and abortions or OC use, respectively, an early OC use was associated with a 43% higher SPF and early abortions were associated with 49% higher SPF. Younger patients had a higher SPF and a higher frequency of aneuploid tumors, but this was found to be because the users of OC had a lower median age at diagnosis. Among never users, no significant age relationship was seen for SPF or the frequency of aneuploidy. For the DNA analyses there is a selection of patients with breast cancer with larger tumors, and therefore the conclusions drawn in this article may not be generalizable to patients with smaller primary tumors, e.g., cases diagnosed at breast cancer screening. The higher tumor proliferative activity and frequency of aneuploidy in early OC users are in line with previously reported findings of worse prognostic indicators and a worse survival in early users of OC compared with other young women with breast cancer.

DNA flow cytometry of follicular non-Hodgkin's lymphoma.

S-phase fraction, an index of cellular proliferation, and DNA ploidy were measured by DNA flow cytometry in a retrospective study of lymph node biopsy specimens from 83 cases (before treatment) of follicular non-Hodgkin's lymphoma, Working Formulation categories B and C. The correlations between these measures and survival, clinical stage, symptoms and histopathological factors were investigated. Aneuploidy was rare (n = 16) and had no effect on length of survival or transformation to high grade lymphoma. The overall mean S-phase fraction was 3.6%; for the whole series increasing S-phase fraction was associated with decreased survival. A high S-phase fraction (more than 5%) in initial biopsy specimens was also associated with an increased risk of subsequent high grade transformation at relapse. There was no difference between the survival or proliferative activity of tumours composed of mainly small cleaved cells compared with those composed of mixed small and large cells. There was no difference in survival or proliferative activity between tumours showing a pure follicular growth pattern and those with a mixed follicular and diffuse growth pattern. Multifactorial analysis showed that an S-phase fraction of more than 5% and B symptoms were the most important factors determining survival in these follicular non-Hodgkin's lymphomas.

Association of c-erbB-2 expression and S-phase fraction in the prognosis of node positive breast cancer.

An immunohistochemical study was performed on 211 primary breast carcinomas for c-erbB-2 expression. All patients had involvement of axillary lymph nodes and all were randomised onto one of the Ludwig Breast Cancer Trials I-IV between July 1978 and August 1981. c-erbB-2 overexpression significantly correlated with high S-phase fraction, four or more positive axillary nodes involved, estrogen receptor negative primaries, progesterone receptor negative primaries, high grade tumours and DNA aneuploidy. With a nine year median follow-up c-erbB-2 positive tumours had worse disease-free survival (p = 0.0002) and overall survival (p less than 0.0001). Multivariate analyses using proportional hazard regression models demonstrated that c-erbB-2 positivity continued to predict a poor outcome even when accounting for the effects of other prognostic factors.

Glycogen-rich clear-cell carcinoma of the breast: A clinicopathologic and flow cytometric study

Six glycogen-rich clear-cell carcinomas (GCC) were found among 439 cases of breast cancer (BC) in a thorough search among a defined urban population. Five of these six patients had axillary lymph node metastases at diagnosis and all five died from their breast cancer within 7 years following the diagnosis. Tumors with histologic features of GCC were larger ( P = 0.03), and they had a large DNA index (>1.3) in flow cytometric DNA analysis more frequently than BCs in general ( P = 0.04). All GCCs were nondiploid and had a high S-phase fraction (>9%, mean 19.2%), which suggests that BCs with glycogen-rich cell features may be more aggressive than BCs in general.

Diploid predominance and prognostic significance of S-phase cells in malignant mesothelioma

70 histologically verified, malignant mesotheliomas were analysed by flow cytometry for DNA content and S-phase fraction (SPF) of tumour cells. 60% ( 42 70 ) were DNA diploid. 18 of the 28 aneuploid tumours were near-diploid with DNA indices of 1.3 or less. SPF could be calculated in 51 cases. SPF was significantly higher in aneuploid (median 16.0%) than in diploid tumours (median 5.6%). DNA ploidy was not a prognostic determinant; survival was the same for both aneuploid and diploid tumours. SPF, however, was significantly correlated ( P = 0.039) with prognosis. Patients who had tumours with a low SPF survived almost twice as long as those with a high SPF. Thus malignant mesothelioma has a peculiar DNA ploidy pattern compared with many other solid tumours, with a predominance of diploid or near-diploid type cells. As in many other tumours, SPF may be used as a clinically relevant prognostic indicator.

Prognostic Indicators in Invasive Breast Cancer

Tumor size and axillary lymph node involvement are the primary determinants of clinical course for most patients. Receptors for estrogen and progesterone are important additional prognostic factors for disease-free survival, overall survival, survival time after initial disease recurrence, and the likelihood of response to hormonal therapy. Histologic grading has merit as a prognostic factor, although poor reproducibility limits its broad application. Promising data have been emerging from the use of flow cytometry to analyze DNA content and proliferative rate. Patients with aneuploid tumors are more likely to have a shorter survival time than patients with diploid tumors. A high S-phase fraction also identifies a subset of patients at increased risk for early relapse. A combined index of ploidy and S-phase may be a more useful guide; together, diploidy and low S-phase identify a subgroup of node-negative patients at very low risk for disease recurrence. A number of oncogenes have been identified in breast cancer; amplification of the HER-2/neu gene or overexpression of the gene product may be an important prognostic indicator for node-positive patients.

Abnormal DNA ploidy and proliferative patterns in superficial colonic epithelium adjacent to colorectal cancer

Superficial colonic cells were taken from normal-appearing mucosa at 2, 5, and 10 cm proximal and distal to colorectal cancer margins in 37 patients. The DNA ploidy and proliferative pattern of each sample were determined using flow cytometry. In 11 patients, histology of mucosal sections from the same sites also was analyzed. We found a higher frequency of aneuploidy than previously reported in mucosa up to 10 cm from a colorectal cancer; 62% (23/37) of the primary cancers were aneuploid, and of these, 48% (11/23) were associated with adjacent aneuploid mucosa. The mucosa adjacent to the 14 diploid cancers had only diploid characteristics. The proliferative activity (as reflected by synthetic (S) phase fraction) of aneuploid cancers (21.1 +/- 2.0% SEM) and aneuploid mucosa as far as 10 cm away (21.2 +/- 2.1% SEM) was higher than in normal controls (10.2 +/- 0.7% SEM) (P less than 0.0005). Parallel cytology excluded shed cancer cells as an explanation for these findings. Histology showed diffuse, generally mild and reactive, mucosal abnormalities in eight of 11 patients. Ploidy did not correlate with histologic abnormalities. The findings of aneuploidy and high S-phase fraction in uninvolved superficial mucosa provide evidence for a field defect in mucosa adjacent to colorectal cancer and support the concept that the large bowel mucosa behaves as a unit in carcinogenesis.

S‐phase fraction of human prostate adenocarcinoma studied with in vivo bromodeoxyuridine labeling

Forty-six patients with adenocarcinoma of the prostate were given an intravenous infusion of the thymidine analogue, bromodeoxyuridine (BrdU), 200 mg/m2, at the time of needle biopsy or transurethral resection to label tumor cells in the DNA synthesis phase. The tumor specimens were stained by an indirect immunoperoxidase method with anti-BrdU monoclonal antibody. The BrdU labeling index, S-phase fraction, was determined by counting the number of BrdU-labeled cells in the tissue sections. S-phase fraction correlates with the results of histologic tumor grade, Gleason score, and growth patterns. The higher S-phase fraction may indicate biologic malignancy. Moreover, the degree of heterogeneity concerning S-phase fraction distribution within prostate cancer tissue could be evaluated and the findings compared with the morphologic appearance. The authors results suggest that the measurement of BrdU labeling index in prostate cancer may prove to be a new objective and quantitative assay for biologic potential of individual tumors.

Cytometric and histopathologic features of tumors detected in a randomized mammography screening program: Correlation and relative prognostic influence

Cytometric determination of S-phase fraction and ploidy type was performed on 430 tumors detected within a randomized trial of mammographic screening. The results were compared to several histopathologic features. A high S-phase fraction was estimated in tumors with a high grade of malignancy and other histopathologic findings related to rapid tumor progression, including lack of tubule formation, a high mitotic index, marked nuclear pleomorphism, multifocal cancer growth, tumor emboli in lymphatic and blood vessels, tumor necrosis, and inflammatory reaction. DNA aneuploidy was correlated with a high malignancy grade, frequent mitoses, a high degree of nuclear pleomorphism, vascular invasion, necrosis, and the presence of noninvasive ductal carcinoma. Both cytometric variables were inversely related to the degree of elastosis. Positive nodes, large tumor size, DNA aneuploidy, a high S-phase fraction, high grade of malignancy, lack of tubule formation, as well as high mitotic index and pleomorphism, presence of multifocal cancer, and vascular invasion, predicted a significantly shorter distant recurrence-free interval after a median follow-up time of 46.6 months. Elastosis and the presence of estrogen and progesterone receptors indicated favorable prognosis. In the multivariate analysis, only lymph node status, tumor size, S-phase fraction, and multifocal growth pattern had independent prognostic value.

DNA index, S-phase fraction, histological grade and prognosis in breast cancer

DNA index and S-phase fraction (SPF) were measured by flow cytometry on paraffin embedded tissue from 140 primary breast tumours. The results of DNA analysis were compared with the size, degree of axillary node involvement, histological grade and steroid receptor content of the tumours, as well as with the patients' subsequent clinical course. Forty-four (31.4%) of the 140 tumours were diploid. S-phase fraction was evaluable for 134 (95.7%). The median SPF of the whole population was 7.1%, with diploid tumours having a significantly lower median SPF (3.2%) than aneuploid (10.1%, P less than 0.001). Both aneuploidy (P = 0.002) and high SPF (P less than 0.001) were strongly associated with high histological grade. There was no significant association between either DNA ploidy or SPF and tumour size, nodal status or steroid receptor content. An SPF below the median was strongly associated with better relapse-free survival (P = 0.008), overall survival (P = 0.004) and survival after relapse (P less than 0.001). Ploidy did not correlate significantly with clinical course. Multivariate analysis using the Cox model suggested that, while SPF gave prognostic information independent of tumour size or nodal status, this independent significance was lost when histological grade was included in the analysis.