Combined therapies for squamous-cell carcinoma of the esophagus, a Southwest Oncology Group Study (SWOG-8037)

Conservative treatment of esophageal cancer with radiation therapy has afforded few long-term survivors. In order to improve outcome, patients with locoregional disease were treated using a combined modality approach. Patients were treated with chemotherapy consisting of a 96-hour continuous infusion of 5-fluorouracil (5-FU), 1,000 mg/m2/d, days 1 to 4 and days 29 to 32; cisplatin 75 mg/m2, day 1 and 29; and radiation 3,000 rad, days 1 to 19. In the absence of progressive disease, patients underwent esophagectomy. One hundred twenty-eight patients were registered of whom 113 were eligible and 106 were evaluable. Toxicity included gastrointestinal (GI) symptoms, mucositis, and myelosuppression. One hundred two patients completed chemoradiotherapy. Following its completion, 11 patients refused surgery, six were considered poor surgical risks, and 14 had progressive disease. Of the remaining 71 patients, 16 had unresectable disease, 13 had residual disease which was incompletely resected, 24 had disease which could be completely resected, and 18 were without disease on pathologic examination. The overall operability rate was 63% and the overall resectability rate, 49%. Surgical mortality was 11%. Eighty-nine of 113 eligible patients have died, with a median survival of 12 months and a 2-year survival of 28%. The median postsurgical survival for all 71 patients was 14 months and was 32 months for those patients attaining complete remission (CR). Combined modality therapy remains an investigational approach. Attempts should be directed at increasing response rate to initial therapy. A randomized comparison between combined modality treatment and radiation therapy is necessary to definitively determine the usefulness of this more aggressive approach.

Chemotherapy for advanced or recurrent gynecologic cancer

Studies of chemotherapy in advanced or recurrent gynecologic cancer have focussed on ovarian, cervical, and endometrial carcinoma. For celomic epithelial carcinomas of the ovary, a large number of cytotoxic agents have been shown to be active. Dramatic improvement in frequency of response with lesser improvement in survival has been noted with the use of cisplatin-based combination chemotherapy as compared to single alkylating agents. More recent studies have evaluated alternative ways to employ cisplatin: higher dose schedules, intraperitoneal administration, and platinum compounds with a potentially better therapeutic index. None has yet been shown superior to a combination of relatively low-dose cisplatin plus an alkylating agent with or without doxorubicin. Cisplatin remains the best studied and most active single agent in patients with squamous cell carcinoma of the cervix. While a number of other agents have demonstrated moderate activity, no combination of drugs has as yet proved superior to single-agent cisplatin. In endometrial carcinoma, progestins and doxorubicin are the most active agents. Tamoxifen, cisplatin, and hexamethylmelamine appear to have moderate activity. No combination has yet been shown to be superior to single agents. Information on chemotherapy for less common gynecologic malignancies is largely anecdotal. Two observations are of note. Cisplatin-based combination chemotherapy is highly active against germ-cell neoplasms of the ovary. Cisplatin also has definite activity against mixed mesodermal sarcoma of the uterus.

A nonautonomous model of population growth

With x = population size, the nonautonomous equation x = xf(t, x) provides a very general description of population growth in which any of the many factors that influence the growth rate may vary through time. If there is some fixed length of time (usually long) such that during any interval of this length the population experiences environmental variability representative of the variation that occurs in all time, then definite conclusions about the population's long-term behavior apply. Specifically, conditions that produce population persistence can be distinguished from conditions that cause extinction, and the difference between any pair of solutions eventually converges to zero. These attributes resemble corresponding features of the related autonomous population growth model x = xf(x).

Assessing the magnitude of intra- and interspecific competition in two coral reef fishes

Many field experiments have tested for effects of competition in nature, but relatively few have used designs allowing simultaneous assessment of the influence of intra- and interspecific competition. Using a response surface design and a press manipulation of densities, we tested effects of competition within and between two species of coral reef fishes (Coryphopterus glaucofraneum and Gnatholepis thompsoni). By tracking individually tagged fishes, we showed that the per-capita effect of intraspecific competitors on individual growth was at least twice as great as the effect of interspecific competitors. Growth rate was better predicted by measures of density that incorporated body size, rather than numerical density, suggesting interference competition. Individuals of both species interacted aggressively with conspecifics at least twice as often as with heterospecifics. Individuals of both species also covered more area while foraging and spent less time in shelter when crowded than when at lower densities. In combination, these behaviours suggest that increased metabolic costs at high density contribute to competitive effects on growth. These competitive interactions occurred among adult fishes, so reduced growth may translate to reduced fecundity as well as reduced survival, and so contribute to population regulation.

Chemotherapy in advanced ovarian carcinoma: current standards of care based on randomized trials

The mainstay of the treatment of advanced (stage III or IV) ovarian carcinoma is systemic therapy. The following review bases conclusions regarding standards of care on large, randomized trials of chemotherapy in advanced ovarian carcinoma. As of 1976, "standard" chemotherapy was single alkylating agent usually with melphalan. Studies of combination chemotherapy failed to show superiority over single alkylating agent until the introduction of cisplatin. The Gynecologic Oncology Group conducted a series of two trials in patients with large-volume disease, the first randomizing patients to either single-agent melphalan or a combination of doxorubicin and cyclophosphamide and the second to doxorubicin plus cyclophosphamide with or without cisplatin. These studies demonstrated superiority for the cisplatin-based combination in terms of overall response rate, clinical complete response rate, progression-free survival, and overall survival. Subsequent randomized trials demonstrated several important facts. First, platinum-based combinations yielded results superior to single-agent cisplatin. Second, a two-drug combination of cisplatin plus cyclophosphamide provides benefit equivalent to the three-drug combination of the same two drugs plus doxorubicin. Third, substitution of carboplatin for cisplatin yields similar results. Finally, dose escalation of chemotherapy by a factor of 2 does not offer a therapeutic advantage. The next major advance after the introduction of the platinum compounds was the demonstration of the activity of taxol, a new agent with a unique mechanism of action and apparent clinical non-cross-resistance with the platinum compounds. A recently completed GOG trial of cisplatin plus cyclophosphamide versus cisplatin plus taxol in patients with large-volume disease shows that the taxol-based combination has a superior overall response rate, clinical complete response rate, rate of achieving a state of no gross residual disease at second-look laparotomy, and progression-free survival. Survival analysis awaits maturation of the data, but the control arm has already been shown to have a median survival of 23.2 months with the median not yet reached for the taxol-based arm. These data suggest that a combination of taxol plus cisplatin should be considered the standard of care for patients with advanced ovarian carcinoma. Ongoing trials seek to define further the role of taxol in frontline chemotherapy for ovarian carcinoma. In conclusion, the standard chemotherapy for advanced ovarian carcinoma should be considered a combination of taxol plus a platinum compound.

Uniform directional alignment of single-walled carbon nanotubes in viscous polymer flow

In this work, we probed the effects of shear flow on the alignment of dispersed single-walled carbon nanotubes in polymer solutions. Two different systems were compared: Single-walled carbon nanotubes dispersed using an anionic surfactant and single-walled carbon nanotubes dispersed using an anionic surfactant and a weakly binding polymer. It was determined that the addition of the weakly binding polymer increased the degree of dispersion of the carbon nanotubes and the ability to induce their alignment when subjected to shear forces.

Evaluation of bone scan as a screening work-up in primary and local-regional recurrence of breast cancer

To evaluate the use of radionuclide bone scan in staging patients with primary and local-regional recurrence of breast cancer, we reviewed the results in 265 patients with primary breast cancer who had the scan either preoperatively or within 6 weeks of surgery, and in 39 patients presenting with their first local-regional recurrence. All patients were clinically staged according to the revised 1983 criteria of the American Joint Committee for Cancer Staging and End-Results Reporting. None of the 92 with stage I and four of 95 patients with stage II had a positive scan. Eleven of 41 with stage IIIA and 13 of 37 with stage IIIB had a positive bone scan. In patients with their first local-regional recurrence, 12 of 39 had a positive scan. Follow-up scans were available in 61 patients with clinical stage I and II breast cancer who had adjuvant chemotherapy for pathological involvement of axillary node. There were six conversions observed in 61 scans obtained during the first year. Seven converted in follow-up scans in 47 patients in the second year. We conclude that although bone scans have a low positive yield in stage I and II breast cancer, their use in the preoperative setting and in the follow-up of patients with axillary node involvement detects early converters. Bone scans are justified in stage IIIA and IIIB breast cancer and in patients being evaluated for local-regional recurrence.

Plant population growth and competition in a light gradient: a mathematical model of canopy partitioning

Can a difference in the heights at which plants place their leaves, a pattern we call canopy partitioning, make it possible for two competing plant species to coexist? To find out, we examine a model of clonal plants living in a nonseasonal environment that relates the dynamical behavior and competitive abilities of plant populations to the structural and functional features of the plants that form them. This examination emphasizes whole plant performance in the vertical light gradient caused by self-shading. This first of three related papers formulates a prototype single species Canopy Structure Model from biological first principles and shows how all plant properties work together to determine population persistence and equilibrium abundance. Population persistence is favored, and equilibrium abundance is increased, by high irradiance, high maximum photosynthesis rate, rapid saturation of the photosynthetic response to increased irradiance, low tissue respiration rate, small amounts of stem and root tissue necessary to support the needs of leaves, and low density of leaf, stem, and root tissues. In particular, equilibrium abundance decreases as mean leaf height increases because of the increased cost of manufacturing and maintaining stem tissue. All conclusions arise from this formulation by straightforward analysis. The argument concludes by stating this formulation's straightforward extension, called a Canopy Partitioning Model, to two competing species.

Effect of intra-arterial cisplatin and 1,3-bis(2chloroethyl)-1-nitrosourea (BCNU) dosage on radiographic response and regional toxicity in malignant glioma patients: proposal of a new method of intra-arterial dosage calculation

The frequency of both neurologic toxicity and therapeutic response due to intra-arterial (IA) chemotherapy is decreased by dose reduction. A method to individualize IA drug dosage is needed to provide each patient with the safest, most effective dose. Most trials of IA chemotherapy for malignant glioma have used body surface area (BSA) to calculate dosage; but brain size and arterial distribution do not correlate well with BSA. Fixed doses of cisplatin and BCNU were used in combination to perform 35 IA infusions in 20 malignant gliomas patients. Doses modified by the number of major intracranial vessels supplied by the infused artery were used in 34 infusions in 19 patients. Patients receiving 150 to 200 mg CP and 300 mg BCNU had an incidence of neurologic deficit of 5.6% if greater than or equal to 3 vessels were supplied by the infused artery compared to 42% for those with only 2 vessels. This crude dose modification maintained efficacy while reducing neurologic toxicity. Further refinement is possible using well established intra-arterial pharmacokinetic principles. Intra-arterial dosing based on volume flow at the site of infusion would yield a more reproducible exposure of the infused capillary bed to a drug than methods currently in use. More consistent drug exposure should reduce toxicity due to over dosing and treatment failure due to under dosing.

Preoperative evaluation with radionuclide brain scanning and computerized axial tomography of the brain in patients with breast cancer

To determine the roles of radionuclide brain scanning and computerized tomography of brain in the pretreatment evaluation of patients with primary and locoregional recurrence of breast cancer, we reviewed the clinical and radiologic findings in 226 patients with breast cancer who underwent one of these scans either preoperatively or within 6 weeks of operation and in 34 patients presenting with locoregional recurrence. Four of 131 radionuclide brain scans in primary breast cancer suggested calvarial metastasis, and the findings were confirmed with bone scans and skull radiographs. One of 95 computerized tomographic scans of the brain showed brain metastasis, and this patient had profound neurologic deficits. With respect to locoregional recurrence, the results of 2 of 23 radionuclide scans and 1 of 11 computerized tomographic scans were positive. All three patients had clinical evidence for brain metastasis. We conclude that in the absence of signs and symptoms, routine evaluation for brain metastasis is not justified in primary and locoregional recurrence of breast cancer.