Final Tumor Size Research Articles

Apparent Diffusion Coefficient: Potential Imaging Biomarker for Prediction and Early Detection of Response to Chemotherapy in Hepatic Metastases

To evaluate the ability of the apparent diffusion coefficient (ADC) to help predict response to chemotherapy in patients with colorectal and gastric hepatic metastases. Institutional review board approval was obtained; all patients provided informed consent. Standard magnetic resonance (MR) imaging and diffusion-weighted (DW) MR imaging were performed before and 3, 7, and 42 days after initiating chemotherapy for 87 hepatic metastases in 23 colorectal and gastric cancer patients (16 men, seven women; mean age, 55.7 years; range, 33-71 years). Lesions were classified as either responding or nonresponding, according to changes in size at the end of therapy. Linear mixed-effects modeling was applied to analyze change in ADCs and size following treatment. The Pearson correlation test was calculated between those ADC parameters and tumor response. Thirty-eight responding and 49 nonresponding metastatic lesions were evaluated. Pretherapy mean ADCs in responding lesions were significantly lower than those of nonresponding lesions (P = .003). An early increase in ADCs (on day 3 or 7) was observed in responding lesions but not in nonresponding lesions (P = .002). Weak but significant correlations were found between final tumor size reduction and both pretreatment ADCs (P = .006) and early ADC changes (day 3, P = .004; day 7, P < .001). ADC seems to be a promising tool for helping predict and monitor the early response to chemotherapy of hepatic metastases from colorectal and gastric carcinomas.

The impact of systemic chemotherapy on circulating epithelial tumor cells (CETC) in breast cancer

11001 Background: The number of CETC can be influenced by natural shedding of cells from the tumor, mobilization of tumor cells by diagnostic and therapeutic manipulations (mammography, surgery), apoptosis and cell death. Here we report on the influence of systemic chemotherapy on the number of CETC. Methods: Tumor cells were quantified with an automated microscope (Laser Scanning Cytometer® or Olympus Scan R) from anticoagulated blood drawn before each new therapy cycle and before and after surgery from 70 patients treated with primary systemic chemotherapy. After red blood cells lysis leucocytes were stained with PE-anti-CD45 and tumor cells with FITC-anti-EpCAM and changes registered as % increase or decrease. The same was performed for 150 patients treated with adjuvant therapy and until 3 weeks after the end of chemotherapy. The response of CETC to therapy was correlated to outcome. Results: Almost all breast cancer patients had CETC before therapy, the number of which correlated with tumor size. During primary systemic therapy the variable initial decrease in cell numbers highly correlated with the final tumor size reduction. In spite of a subsequent re-increase in all neoadjuvantly treated patients, the reduction in CETC also predicted for relapse free survival. In response to adjuvant systemic therapy CETC showed three typical groups of response pattern. 1. Reduction in CETC more than tenfold 2. Marginal changes throughout therapy. 3. Increase or initial response and subsequent re-increase more the tenfold in numbers of CETC. During the post-therapy observation interval of 4.5 years, no relapse occurred in the group of patients with good response, whereas most relapsing patients are found in group 3 with an 11 - 16fold hazard ratio. Conclusion: Monitoring CETC will not only provide the earliest and most reliable indicator of successful neoadjuvant treatment and spare patients unnecessary treatment. It also, for the first time, allows monitoring of therapy efficiency in the adjuvant situation which is highly predictive for relapse free survival. This warrants further therapy studies to control what patients may benefit from additional or modified therapy already before metastases appear. No significant financial relationships to disclose.

A NOD/SCID Model of Primary Human Breast Cancer

Background: Breast cancer kills about 400 000 people annually worldwide. Whilst the conventional therapy of surgery, radiation, chemotherapy and hormone therapy has increased survival rates dramatically, the relapse rate is intol- erably high. New therapies, particularly immunotherapies, required to combat this residual disease would ideally be tested on an animal model. Current animal models of human breast cancer available for testing new therapies are unreliable. We therefore sought to develop a protocol that will enable the reliable and reproducible production of a xenograft murine model of human breast cancer. Methods: Female NOD/SCID mice, under specific pathogen-free conditions, were inoculated subcutaneously in the ingui- nal mammary fat pad area with either dissociated primary breast tumours or the breast cancer cell line MCF7. Variables tested included irradiation of mice prior to inoculation, differing tumour cell numbers and the use of the commercial basement membrane Matrigel. Results: 100% engraftment and growth of both MCF7 cells and dissociated primary breast tumour cells, coinoculated with Matrigel, was achieved regardless of whether the mouse was irradiated or not, however larger tumour volume was achieved in the non-irradiated mice. The largest inoculum, 5 x 10 6 cells of MCF7 cells, gave the largest tumours after 3 months in situ (p=0.006). The number of cells injected from primary tumours did not correlate with final tumour size. Both MCF7 and primary human breast tumours exhibited the layered nature of breast tumours, with living cells on the pe- riphery and necrotic cells in the interior. MCF7 cells that engrafted maintained their ER+, CD24+, CD44+ BC2+ (MUC1+) status after in vivo growth. All tumours became vascularised but no metastasis was evident. Conclusions: This is a simple and reliable protocol that ensures human breast tumour growth in the NOD/SCID mouse. This model is valid, in that the tumours are orthotopic, they have the layered nature of human breast tumours, become vascularised and maintained the surface and nuclear marker status tested for. It has potential as a valid human breast can- cer test bed for preclinical testing of immunotherapies and anti-angiogenesis agents.

Optimal delivery of chemotherapeutic agents in cancer

Cancer refers to a set of diseases where normal cells of the body lose mechanisms which are responsible for controlling their growth and motility. Chemotherapy aims to kill these abnormal or cancer cells, however normal cells and healthy tissues are also adversely affected. Systematic modelling and optimization approaches can be employed to obtain effective chemotherapeutic protocol that minimizes the tumour cell population while limiting the damage to the normal cells. In this paper, two models for cancer chemotherapy are considered and the effect of the time of drug administration on the final tumour size is analyzed. The first model is cell cycle non-specific and considers all the cancer cells as belonging to one compartment whereas the second model is cell cycle specific and takes into account the effect of the drugs that act on cells at certain specific stages of the cell cycle. An optimal control problem is also formulated and solved for both the models so as to obtain the chemotherapeutic schedule which minimizes the final tumour size while taking into account the constraints on drug resistance and toxicity. For the first model a mixed integer dynamic optimization problem and for the second model a dynamic optimization problem are solved. The optimal chemotherapeutic drug administration profiles and the variation of number of cells with time are obtained and analyzed in detail.

DC MEG indicators of tumor growth and chemotherapy in rat model

Abstract The objective of this study was to determine if DC MEG can detect injury currents from tumor growth and chemotherapy in a rat model. Male Fisher rats were randomly divided into five groups: Groups One and Two were implanted with 9 L gliosarcoma cells. Group Three, surgery controls, received saline injections. Group Four were normal controls with no surgery. Group Two rats were treated with chemotherapy (1,3 Bis[2-chloroethy]-1-nitrosuorea, BCNU) five days after tumor implantation. Group Five rats had no surgery or tumor but received the same chemotherapy as Group Two. Baseline DC MEG measurements were taken with a six-channel animal neuromagnetometer using a stereotaxic fixture. DC MEG field measurements were recorded before and after lateral translation of the head 3 cm away from the sensor array and repeated 12–15 times to calculate average absolute field shifts. Ambient and fixture magnetic noise was subtracted from the measured rat signals to determine absolute DC MEG shifts. Post surgery, measurements continued every two days until sacrifice. Anatomical MRIs were performed on selected rats to estimate tumor volume at 4–6 day intervals throughout the experiment. Histology was performed on the sacrificed brains to evaluate final tumor size. DC MEG shifts were seen in the tumored and chemotherapy treated tumored rats, Groups One and Two. In these groups, the field shifts continued until sacrifice. In a few of the saline control rats (Group Three), DC Magnetic Field shifts were also seen but these correlated to rats with surgical side effects, i.e. weight loss or illness, and resolved when the rats recovered. No significant DC shifts were seen in the normal control rats (Group Four) or the chemotherapy with no tumor rats (Group Five). DC shifts seen in Group One and Two animals suggest continued injury currents in the rats' brains.

Inhibition of Burkitt's lymphoma cells growth in SCID mice by a PNA specific for a regulatory sequence of the translocated c-myc

In Burkitt's lymphoma (BL) cells due to a t(8;14) chromosomal translocation c-myc is often placed in proximity to the Emu enhancer of the Ig locus and upregulated. We demonstrated that in BL cells a peptide nucleic acid (PNA), complementary to intronic Emu sequences (PNAEmuwt), specifically blocks the expression of the c-myc oncogene under the Emu enhancer control and inhibits BL cell growth in culture. Here, we investigated whether PNAEmuwt was also able to block tumor growth in SCID mice inoculated with human BL cell lines. After subcutaneous inoculum in mice BL cells reproducibly form tumors. Both pre-treatment of BL cells with PNAEmuwt before inoculum and chronic intravenous administration of PNAEmuwt to mice already inoculated with BL cells selectively caused increased latency of tumor appearance and decreased final tumor size. Tumors from PNAEmuwt-treated animals showed substantial areas of cell necrosis and of c-myc downregulation. Inhibition of tumor growth was specific and was not observed with PNAEmumut carrying sequence mutations and in BL cell lines where the translocated c-myc is not under the control of the Emu enhancer. These data confirm the potential therapeutic value of PNA targeted to regulatory non-coding regions.

Accurate determination of breast cancer size: The role of histopathology and imaging

One critical role played by the pathologist in contemporary breast cancer management is that of providing accurate tumour measurements for staging and prognosis. Numerous factors have the potential to affect the final pathologist-recorded tumour size including diligence in measurement, tumour histology and growth pattern, tissue fixation and processing, prior biopsy and prior therapy. The pathologist should strive to provide three-dimensional tumour measurements in 0.1 cm increments from the gross specimen and then confirm these measurements microscopically whenever possible. In the era of breast conservation and emerging ablative therapies, the pathologist should also be familiar with the size-determining capability of various breast imaging techniques and their correlation with pathology. In determining final dimension, the pathologist is in a favourable position to verify or modify the size of a breast tumour based on the sum of information from all pathology specimens and, if appropriate, to correlate size with the patient's imaging studies.

How do we measure a residual tumor size in Histopathology (the gold standard) after neoadjuvant chemotherapy?

Accurate reporting of the residual tumor size by pathologists after neoadjuvant chemotherapy is an important component of a breast cancer. Recent literature reported comparisons regarding the accuracy of clinical and radiological residual tumor size findings using the histopathology as a "gold standard". However, the histopathological methods of measuring the residual tumor size are not standardized. Most pathologists use the tumor size measured by the gross examination. We collected 32 patient samples and compared the residual tumor size by gross and microscopic pathologic examinations. Using microscopic tumor size as the gold standard, our study showed gross tumor size is overestimated in 25%, underestimated in 56% and correlated to the final microscopic tumor size in 19% of the cases after neoadjuvant chemotherapy. Determining accurate residual tumor size to estimate pathologic response to chemotherapy is essential. We attempted to provide guidelines for pathology reporting post-neoadjuvant chemotherapy on breast cancers.

Dynamic contrast-enhanced MRI and sonography in patients receiving primary chemotherapy for breast cancer

We compared dynamic contrast-enhanced MRI (DCE-MRI) and sonography (US) for monitoring tumour size in 21 patients with breast cancer undergoing primary chemotherapy (PCT) followed by surgery. The correlation between DCE-MRI and US measurements of tumour size, defined as the product of the two major diameters, was 0.555 (P=0.009), 0.782 (P<0.001), and 0.793 (P<0.001) at baseline, and after two and four cycles of PCT, respectively. The median tumour size was significantly larger when measured by DCE-MRI than by US at baseline (1472 vs 900 mm(2), P<0.001) and after two cycles of PCT (600 vs 400 mm(2), P=0.009). After PCT, the median tumour size measured by the two techniques was similar (256 vs 289 mm(2) for DCE-MRI and US, respectively, P=0.859). The correlation with the histopathological major tumour diameter was 0.824 (P<0.001) and 0.705 (P<0.001) for post-treatment DCE-MRI and US, respectively. Measurements of the final major tumour diameter by DCE-MRI tended to be more precise, including cases achieving a pathological complete response. Randomized trials are warranted to establish the clinical impact of the initial discrepancy in tumour size estimates between DCE-MRI and US, and the trend towards a better definition of the final tumour size provided by DCE-MRI in this clinical setting.

Breast cancer in patients with residual invasive carcinoma is more accurately staged with additive tumor size assessment.

Accurate assessment of tumor size for patients with breast cancer undergoing re-excision following breast-conserving therapy is important for appropriate staging and adjuvant treatment. We investigated the accuracy of additive vs. nonadditive size assessment in determining final tumor stage. Patients with infiltrating carcinoma in the initial excision and in at least one additional re-excision (re-excision positive; n = 89) had tumor size assessed with additive and nonadditive techniques. This group was compared with patients undergoing re-excision but without identifiable residual carcinoma (re-excision negative; n = 105) regarding rates of lymph node (LN) metastasis. The re-excision positive patients had a different median final tumor size depending on the size assessment technique used (nonadditive: 1.8 cm; additive: 3.0 cm; P <.0001). Both groups of patients had a median tumor size consistent with T1c staging in nonadditive size assessment. However, re-excision positive patients had a significantly higher incidence of LN metastasis (P <.05) than did re-excision negative patients. Both groups were then separated into T1 and T2 stages and the LN metastasis rates were assessed. Compared with nonadditive size assessment, additive size assessment distributed re-excision positive patients into T stages whereby the LN metastasis rates more closely approximated those of re-excision negative patients (T1, 3% vs. 6% difference; T2, 4% vs. 13% difference). With regard to LN metastasis, staging for patients with residual invasive carcinoma in re-excision specimens is more accurate with additive tumor size assessment.

Monitoring the size and response of locally advanced breast cancers to neoadjuvant chemotherapy (weekly paclitaxel and epirubicin) with serial enhanced MRI.

To determine if early cancer size reduction seen on enhanced magnetic resonance imaging (MRI) can serve as a response predictor and to correlate final tumor sizes on MRI and excised gross tumor size to microscopic findings in patients with locally advanced breast cancers treated with preoperative neoadjuvant chemotherapy. Thirty-three patients with advanced breast cancer entered this prospective chemotherapeutic study. Serial, dynamic, enhanced MRI was performed before chemotherapy induction, after the first course of chemotherapy and after the third course of chemotherapy prior to surgery. Responses were measured by image subtraction of tumor size on subsequent axial MRIs using the response evaluation criteria in solid tumors (RECIST). Early tumor size reduction, percentage of relative early tumor size reduction and final tumor size response were calculated and analyzed statistically. Sizes of residual tumors measured on MRI and gross tumors in excised breasts were correlated with microscopic findings. Based on tumor sizes measured with enhanced MRI, four complete responders (CR), 19 partial responders (PR) and 10 non-responder were documented. Twelve (52%) of the 23 responders (CR and PR)had reached the criteria for PR (> or = 30% size reduction) after the first course of chemotherapy. All CR had a marked early size reduction (ESR) of more than 45%. Using the receiver operating characteristic (ROC) curve, a good cutoff point for early tumor size reduction was 7.4 cm, with a false positive rate of 0.1 and a false negative rate of 0.13. The percentage of ESR was 8.8%, with a false positive rate of 0.1 and a false negative rate of 0.09. Residual tumor size on MRI correlated well with microscopic findings (r = 0.982, p < 0.001) and gross tumor size in excised breasts correlated moderately with microscopic findings (r = 0.640, p < 0.001). Serial, dynamic, enhanced MRI monitoring of chemotherapeutic response in patients with locally advanced breast cancer can be used to assess early response to chemotherapy and post-chemotherapy tumor size change. Although the residual tumor size on MRI correlated well with the microscopic findings, surgical determination of residual cancer load is still recommended to avoid underestimation.

Breast carcinoma: value of adjuvant therapy after mastectomy? Overview of personal results over > or = 20 years

Analysis of 626 consecutive locoregional postoperative irradiated patients after mastectomy. 49.5% (310/626) were without further therapies, 32.8% (205/626) received TAM and 17.7% (111/626) an adjuvant chemotherapy +/- TAM. All tumours were classified on the basis of the pathologic-anatomical spreading. Median age 59 (25-91) years, follow-up 180 (60-265) months. Local relapses 7.1%, distant metastases 40.4%, death as consequence of breast cancer 35.6%, in 20.3% death of other causes. Cause specific survival (CSS) by negative axilla in 76%, by 1 to 3 LN+ metastases in 55% and by > or = LN+ in 30%. On the basis of the final results, lymphnode status, vascular invasion and initial tumor size have been the most important risk factors of prognostic relevance. Their rate of local relapses have been twice to six times as high, the distant metastasis 1.5 to 2 times more frequent. Immense differences too in comparing the CSS after 20 years: high risk collective 26 to 47%, low risk 65 to 72%. No statistical difference has shown in the low risk collective between the therapy groups. As referred back to the initial axillary status, 39.6% (248/626) have been without positive LN at the time of mastectomy. 76.2% (189/248) have remaind without distant metastases (DM), in 78.4% (149/190) without adjuvant therapy after locoregional irradiation. In 60.4% (378/626) the axilla was attacked. 48.7% (184/378) remained without distant metastases. 19.6% (36/184) with chemotherapy, 49.4% (91/184) with TAM and 31% (57/184) without supplemented systemic therapies. With 1 to 3 LN+ 58.4% (108/185) neither clinical nor radiological dissemination proven. It may be due to the efficiency of chemotherapy and TAM that only in 38.2% (13/34) respectively in 34.3% (23/67) distant metastases have been proven. In contrary after > or = 4 LN+ the chemotherapy-group has had 76.2% (48/63) and by combination with vascular invasion 85.2% (23/27) distant metastases. An opposite effect cannot be excluded. A positive axilla may but doesn't have to be a harbinger of tumor generalisation, since on third has remained without distant metastases despite of the lack of adjuvant therapies after locoregional irradiation. Is it possible a consequence of the irradiation too? No side effects of importance: Absence of plexopathies, no cardiotoxicity, 0.8% rib-necrosis after high dose irradiation as a consequence of R1-resections. There are no reasons for a renunciation of postmastectomy irradiation because of its secondary effects.

Natural history of colorectal carcinoma: can the tumor volume doubling time be predicted by radiologic findings or immunohistochemical variables?

The factors influencing the growth rate of colorectal carcinoma have not been determined. The aim of this study was to clarify the relationship between the doubling time (DT), morphology, and proliferating cell nuclear antigen, Ki-67 and p53 immunohistochemistry in colorectal carcinoma. Thirty-three patients (37 lesions) were studied retrospectively. The DT was calculated and correlated with the initial and final tumor size, morphologic shape, and immunohistochemical results. The DT ranged from 2.4 to 48.0 months (mean: 12.0 months). The mean DT of the early-stage carcinomas was significantly longer than that of the advanced carcinomas. In the latter group, both slowly growing and rapidly growing tumors were observed. The DT showed no correlation with the initial or final size and shape of the tumors on radiographs, or with the immunohistochemical results. Our data revealed that it is not possible to evaluate the growth rate of colorectal carcinomas based on their morphological shape, cellular proliferative activity, or tumor suppressor gene activity.

An application of genetic algorithms to optimization of cancer chemotherapy

In recent years much work has been don; on modelling the growth of malignant tumours with a view to predicting their development and optimizing the effect of chemotherapy on their alleviation. One approach has been to treat the tumour as a non‐linear system and the drug treatment as a control strategy. This has led to the use of calculus of variations and optimization techniques to produce optimal and sub‐optimal drug regimes. This paper uses the Gompertz equation as a model of tumour growth and attempts to minimize final tumour size in the presence of drug constraints. The optimization technique is novel in that it uses the genetic algorithm method to devise optimal drug regimes where individual regimes are encoded as ‘chromosomes’ and evolution is simulated in order to improve treatment strategies.

The use of ultrasound for monitoring breast tumour response to pro-adjuvant therapy

In a prospective study, use of serial ultrasound (US) for monitoring tumour response to pro-adjuvant chemotherapy was assessed in 16 patients. Comparison was made with mammographic and pathological tumour size measurements. Clinical and radiological response to treatment was assessed using UICC (International Union Against Cancer) criteria. Comparison of clinical and US response to treatment showed some agreement in 60% and disagreement in 40%. This was comparable with clinical versus mammographic responses (55% and 45%). Correlation between calliper and pathological measurement was similar to that between US and pathological measurement (r = 0.51, P = 0.05; r = 0.50, P < 0.05). Mammography showed poorer correlation (NS). For assessment of final tumour size, US clinical measurements were comparable and better than mammography. US may be a useful tool in monitoring the response of breast tumours to pro-adjuvant therapy.

Effects of inoculation site and Matrigel on growth and metastasis of human breast cancer cells.

The co-injection of extracellular matrix components, such as Matrigel, with human tumour cells into nude mice has been reported to facilitate tumour formation and growth, but it is unknown whether such components exert similar effects on tumour progression and metastasis. Metastatic behaviour is known to be enhanced when tumour cells are implanted orthotopically, and it is inferred that full and efficient expression of this phenotype may involve some interactions with local connective tissue matrix. It was therefore decided to investigate whether manipulation of the mesenchymal environment by co-injection of extracellular matrix components, in the form of Matrigel, with human breast cancer cells into orthotopic or ectopic sites could augment their metastatic performance, as well as their growth at the site of inoculation. Standard aliquots of 10(6) cells of the polyclonal human breast carcinoma cell line MDA-MB-435, and of four clonal cell lines, two metastatic and two non-metastatic derived from it, were injected with and without Matrigel, orthotopically or subcutaneously into nude mice. The latent period of tumour formation at the inoculation site as well as final tumour size and metastatic performance at autopsy, 140 days after inoculation, were then assessed. The prevalence of metastasis of the parent, polyclonal, cell line and of its metastatic clones was increased if the cell inoculum was mixed with Matrigel. Non-metastatic clones were not induced to become metastatic by this treatment, but local tumour growth at the site of inoculation was enhanced in all experimental groups receiving Matrigel. Orthotopic inoculation acted synergistically with Matrigel to maximise both tumour growth and metastatic behaviour. The composition of the local extracellular matrix at the site of tumour growth influenced expression of the metastatic phenotype by cells which are constitutionally capable of this behaviour, but did not induce it in ones which are not. Previous reports that local tumour growth is facilitated by enrichment of the mesenchymal matrix are confirmed. The mechanisms by which such effects are exerted are worthy of study, to ascertain whether they might be subject to clinical manipulation designed to retard tumour growth and dissemination.

Enhancement of Antitumor Effects of Combined Chemoimmunotherapy

The spontaneously metastatic murine pancreatic tumor, PAN 2, was used to evaluate established regimens of combined chemoimmunotherapy with 5-fluorouracil (5-FU) and levamisole and new protocols based on the immunomodulator, thymopoietin pentapeptide (TP-5). The combination of 5-FU and levamisole reduced the final tumor size by 32% and the mean number of lung metastases by 71%. Based on flow cytometric analysis, the combination treatment increased the percent of helper/inducer (CD4+) lymphocytes and reduced the number of effector (suppressor/cytotoxic) lymphocytes (CD8+). A second combination using 5-FU and TP-5 produced a reduction in tumor growth rate of 52%, with an 88% suppression of lung metastases with TP-5/5-FU (vs. levamisole/5-FU) treatment. The TP-5 treatment also increased splenic T-lymphocyte responsiveness to nonspecific mitogens by 2.3-fold. These results suggest a correlation between enhanced T-lymphocyte functional parameters and reduced tumor growth and metastatic spread produced by these combination therapies. Since TP-5 has been demonstrated to be a superior immunomodulator compared to levamisole, the greater therapeutic effect of TP-5 vs. levamisole further supports the postulated role of immunopotentiation in the success of combined chemoimmunotherapy.

Design of Multidrug Cancer Chemotherapy Via Optimal Control

In this paper we consider the problems of modellinq the tumour growth and optimizing a combination chemotherapy. Our approach consists in constructing a Multicompartmental model based on cell kinetics and estimating its parameters by using data collected from in vitro measurements of tumour population. An optimal control problem with a cost functional reflecting the patient's lite expectancy, i.e., a compromise between the final tumour size and toxicity effects, is formulated and an iterative algorithm searching a multidrug dosage schedule satisfying necessary conditions of optimality is constructed. Although no systemic considerations are taken into account (and therefore a comparison with clinical experience is difficult) this approach is considered as a valuable step towards the building of a decision support system.

Malignant transformation of guinea pig cells after exposure to ultraviolet-irradiated guinea pig cytomegalovirus

Guinea pig cells were malignantly transformed in vitro by ultraviolet (uv)-irradiated guinea pig cytomegalovirus (GPCMV). When guinea pig hepatocyte monolayers were infected with uv-irradiated GPCMV, three continuous epithelioid cell lines which grew in soft agarose were established. Two independently derived GPCMV-transformed liver cells and a cell line derived from a soft agarose clone of one of these lines induced invasive tumors when inoculated subcutaneously or intraperitoneally into nude mice. The tumors were sarcomas possibly derived from hepatic stroma or sinusoid. Transformed cell lines were also established after infection of guinea pig hepatocyte monolayers with human cytomegalovirus (HCMV) or simian virus 40 (SV40). These cell lines also formed colonies in soft agarose and induced sarcomas in nude mice. It is concluded that (i) GPCMV can malignantly transform guinea pig cells; (ii) cloning of GPCMV-transformed cells in soft agarose produced cells that induced tumors with a shorter latency period but with no alteration in growth rate or final tumor size; and (iii) the tumors produced by GPCMV-and HCMV-transformed guinea pig cells were more similar to each other in growth rate than to those induced by SV40-transformed guinea pig cells.

Syntheses and biological activities of 7 beta-methyl steroids.

The preparation of 7 beta-methyl-5 alpha-dihydrotestosterone acetate and its 2-thia-A-nor analogue is described. Biological evaluation shows that a 7 beta-Me largely decreases myotrophic-androgenic activity in both 5 alpha-dihydrotestosterone and the 2-thia-A nor analogue. Testing for antitumor activity shows that the reduction in breast tumor weight was not significant for either compound, but the final tumor size in the animals treated with 7 beta-methyl-2-thia-A nor steroid at 10 (mg/kg)/day was significantly reduced. The effects of 7 beta-Me steroids on the various organ weights are also described. The influence of 7 beta-Me substituent on the biological activities of androgens may be mediated through direct interaction of the substituent with the receptor surface in contact with the third dimension of the steroid molecule.