The transfer of unsterilized material from Mars to Phobos: Laboratory tests, modelling and statistical evaluation.

Sample return missions to Phobos are the subject of future exploration plans. Given the proximity of Phobos to Mars, Mars' potential to have supported life, and the possibility of material transfer from Mars to Phobos, careful consideration of planetary protection is required. If life exists, or ever existed, on Mars, there is a possibility that material carrying organisms could be present on Phobos and be collected by a sample return mission such as the Japanese Martian Moons eXplorer (MMX). Here we describe laboratory experiments, theoretical modelling and statistical analysis undertaken to quantify whether the likelihood of a sample from Phobos material containing unsterilized material transferred from Mars is less than 10-6, the threshold to transition between restricted and unrestricted sample return classification for planetary protection. We have created heat, impact and radiation sterilization models based on the Phobos environment, and through statistical analyses investigated the level of sterilization expected for martian material transferred to Phobos. These analyses indicate that radiation is the major sterilization factor, sterilizing the Phobos surface over timescales of millions of years. The specific events of most relevance in the Phobos sample return context are the 'young' cratering events on Mars that result in Zunil-sized craters, which can emplace a large mass of martian material on Phobos, in a short period of time, thus inhibiting the effects of radiation sterilization. Major unknowns that cannot yet be constrained accurately enough are found to drive the results - the most critical being the determination of exact crater ages to statistical certainty, and the initial biological loading on Mars prior to transfer. We find that, when taking a conservative perspective and assuming the best-case scenario for organism survival, for a 100 g sample of the Phobos regolith to be below the planetary protection requirement for unrestricted sample return, the initial biological loading on Mars must be <8.2 × 103cfu kg-1. For the planned MMX mission, a ∼10 g sample to be obtained from a 25-30 mm diameter core as planned would require an initial martian biological loading to be <1.6 × 104cfu kg-1, in order to remain compliant with the planetary protection threshold.

The role of dose intensity in determining outcome in intermediate-grade non-Hodgkin's lymphoma.

To determine whether the dose intensity of chemotherapeutic regimens correlates with the complete remission rate in adult patients with advanced-stage intermediate-grade lymphoma, reports of comparative trials of therapy were reviewed. Reports were identified using MEDLINE, through references from review articles, and through review of selected abstracts. Twenty-two studies including 14 randomized and eight cohort trials were analyzed to assess projected dose intensity. Four other studies were analyzed to assess the role of received dose intensity. Dose intensities were calculated using described methods and correlated with complete remission rates. Individual trials were assessed using "levels of evidence." A metaanalysis of randomized trials and a cross-trial analysis of all comparative trials using a weighted least squares linear regression were performed. Using levels of evidence, support was obtained for the hypothesis that dose intensity correlates with the remission rate from two trials in which dose intensity was "indirectly" tested. As these studies did not "directly" test dose intensity, confounding variables, including those arising from the assumptions made in calculating dose intensity, cannot be excluded. Metaanalysis showed a relative probability of achieving complete remission of 1.34 (95% confidence interval, 1.13 to 1.58) favoring the pooled arm of high dose intensity. Cross-trial analysis showed a relatively weak association between dose intensity and remission rate (r = .49, P = .0001). Two of four reports retrospectively assessing received dose intensity suggested that increased dose intensity is associated with superior remission rates. These analyses suggest that dose intensity may correlate with the remission rate in advanced-stage intermediate-grade lymphoma. However, properly designed trials directly testing dose intensity have not been performed and are needed to confirm this hypothesis.

Modulation of the antitumor effect of methotrexate by low-dose leucovorin in squamous cell head and neck cancer: a randomized placebo-controlled clinical trial.

Randomized trials comparing high-dose methotrexate (HDMTX) plus leucovorin (LV) with standard-dose methotrexate (SDMTX) have not detected a therapeutic advantage for the HDMTX arm despite compelling evidence from experimental systems. We hypothesized that these negative trials might reflect modulation of the antitumor effect of methotrexate (MTX) by LV. To test this we randomized 61 patients with locally advanced and recurrent squamous cell head and neck cancer to receive SDMTX (40 mg/m2 weekly for 8 weeks) and either LV or placebo "rescue" starting 24 hours later. Of the 61 randomized patients, there were protocol violations in two cases, leaving 59 patients evaluable for response using standard criteria, and for toxicity using the Eastern Cooperative Oncology Group (ECOG) scale. Of the 29 patients randomized to MTX plus LV, there were five responders (17.2%) compared with 11 of 30 (36.7%) patients randomized to MTX plus placebo (P = .047). Response was influenced independently by age, gender, and by previous treatment. Toxicity overall was more severe in patients randomized to MTX plus placebo (P = .016). This was accounted for primarily by differences in toxicities related to bone marrow function (neutrophil and platelet counts), stomatitis, and elevations of liver function tests. MTX therapy was more often interrupted for toxicity in the placebo group (P = .007) and discontinued for progressive disease in the LV group (P = .07). These results indicate that at the doses of MTX and LV used, LV modulates the antitumor effect as well as the toxicity of MTX in patients with head and neck cancer.

Methotrexate/fluorouracil scheduling influences normal tissue toxicity but not antitumor effects in patients with squamous cell head and neck cancer: results from a randomized trial.

To test the hypothesis that sequential scheduling of methotrexate (MTX) and fluorouracil (FU) produces a synergistic antitumor effect, we randomized 113 patients with recurrent or locally advanced squamous cell carcinoma of the head and neck to receive MTX-FU either 18 hours apart or simultaneously, with leucovorin rescue. There were 100 patients with locally advanced newly presenting disease and 13 patients with recurrence. Excessive toxicity was observed in the first 11 patients who received MTX 250 mg/m2 administered intravenously (IV) and leucovorin at 36 hours, therefore all subsequent patients received MTX 200 mg/m2 administered IV and leucovorin at 24 hours. FU 600 mg/m2 IV was administered to all patients, and treatment was given on days 1 and 8 of 21-day cycles. The treatment groups were well balanced for known prognostic variables. The response rate was 47.3% (26 of 55) for simultaneous v 44.8% (26 of 58) for sequential therapy. These results exclude a 20% difference in response rate favoring sequential therapy at P = .04. There was no observed difference in survival between the two treatment arms (P = .55) with a minimum follow-up of 8 months. Toxicity was greater in patients who received sequential therapy, and the difference was confined to the gastrointestinal (GI) tract. A comparison of the distribution in maximum Eastern Cooperative Oncology Group (ECOG) toxicity scores during chemotherapy for the two treatment groups showed greater stomatitis (P = .001), diarrhea (P = .04), and overall toxicity (P = .02) for sequential treatment without an observed difference in bone marrow toxicity. The results of this trial indicate that sequential MTX-FU is not superior to simultaneous therapy for the treatment of patients with head and neck cancer. Biochemical modulation of MTX-FU by drug scheduling may occur in vivo and may be organ specific.

Quality of life in stage II breast cancer: an instrument for clinical trials.

A questionnaire has been developed for use as an outcome measure in clinical trials of adjuvant chemotherapy in women with stage II breast cancer. The selection of items for this Breast Cancer Chemotherapy Questionnaire (BCQ) was based on the problems and experiences felt to be most important by women undergoing adjuvant chemotherapy. The BCQ consists of 30 questions that focus on loss of attractiveness, fatigue, physical symptoms, inconvenience, emotional distress, and feelings of hope and support from others. The BCQ, other instruments that evaluate quality-of-life (Spitzer, Karnofsky, and Rand), and patient and physician global assessments were administered serially to 418 patients taking part in a randomized trial comparing a 12-week regimen and a 36-week regimen of adjuvant chemotherapy. The validity of the BCQ is supported by its correlation with the Rand Emotional (r = .58), Rand Physical (r = .60), and Spitzer (r = .62) questionnaires. The BCQ correlated more strongly with global ratings of both physical and emotional function by the patients and their physicians than the other instruments. A comparison of the quality-of-life outcomes of patients in the two treatment groups in the period beyond 3 months after initiation of treatment, when one group had completed the treatment course and the other was still on treatment, revealed that the BCQ and Karnofsky were the only instruments able to demonstrate differences between the groups (P less than .0001). Hence, the BCQ is a valid and responsive method of assessing treatment-related morbidity in patients receiving adjuvant chemotherapy for stage II breast cancer.

Delayed recovery of peripheral blood cell numbers after adjuvant cytotoxic chemotherapy for stage II breast cancer.

A study was made on the recovery of the bone marrow after adjuvant chemotherapy given to 30 post-mastectomy patients with stage II breast cancer treated with either melphalan or melphalan and methotrexate at 6-weekly intervals for 1 year. Counts of peripheral blood cells were made serially during treatment and then for a further 2 years after stopping chemotherapy. Mean counts for all cell types fell during chemotherapy and recovery was long-delayed. Thus 24 months after chemotherapy, mean counts for total leucocytes and platelets were significantly lower than mean pretreatment counts and counts for a normal female population, and the count for neutrophils was significantly lower than the count before treatment; after 24 months mean counts for lymphocytes were not significantly depressed. Melphalan was assumed to be the agent responsible. Slow haematological recovery after cessation of adjuvant chemotherapy with one particular regimen points to the need for including long-term post-chemotherapy observation of the bone marrow in the assessment of adjuvant chemotherapy programmes.

Effect on natural killer and antibody-dependent cellular cytotoxicity of adjuvant cytotoxic chemotherapy including melphalan in breast cancer.

Natural killer (NK) cell activity and antibody-dependent (K) cell activity were studied sequentially in 30 patients with early node-positive breast cancer entered into an adjuvant chemotherapy trial. The drugs used were melphalan, and melphalan with methotrexate, given for 12 months. Estimations were made 3-monthly during chemotherapy, and then at 15 and 24 months to assess recovery. Mean values for NK-cell activity during chemotherapy were significantly lower than the mean pre-chemotherapy baseline value at all time-points from 3 to 15 months, but there was recovery by 24 months. Mean values for K-cell activity during chemotherapy did not appear to differ from the mean pre-chemotherapy value, but variability in individual values was high. Over a 4-year follow-up period, a comparison of 16 patients who did not develop recurrent breast cancer with 14 who did showed that NK-cell activity was significantly lower in the latter group 12 months after the start of chemotherapy.

The thrombogenic effect of anticancer drug therapy in women with stage II breast cancer.

Thromboembolic disease has long been recognized as a complication of cancer. Recent reports have suggested that drugs used in the treatment of cancer, including chemotherapeutic agents and hormones, may contribute to this risk, but it has not been possible to separate the effect of these drugs from that of the cancer. We performed a randomized trial comparing 12 weeks of chemohormonal therapy (using cyclophosphamide, methotrexate, fluorouracil, vincristine, prednisone, doxorubicin, and tamoxifen) with 36 weeks of chemotherapy (using cyclophosphamide, methotrexate, fluorouracil, vincristine, and prednisone) in patients with Stage II breast cancer. Among 205 patients randomly assigned to treatment, there were 14 episodes of thrombosis (6.8 percent). These 14 episodes occurred during 979 patient-months of chemotherapy; by comparison, there were no events during 2413 patient-months without therapy. During the first 12 weeks of the study, five patients in the 12-week group and four patients in the 36-week group had thrombosis. During the subsequent 24 weeks, when only patients in the 36-week group were still receiving chemotherapy, there was no thrombosis in the 12-week group, but there were five additional events in the 36-week group (P = 0.03). These findings suggest that chemotherapy contributes to thrombosis in patients with breast cancer.

Effect on immunologic and other indices of adjuvant cytotoxic chemotherapy including melphalan in breast cancer.

Thirty patients with histologically proven node-positive early breast cancer (Stage II) were treated by total mastectomy and axillary clearance and adjuvant chemotherapy regimens including melphalan for 1 year. These patients were studied sequentially, at 3-month intervals, for up to 2 years to assess effects of cytotoxic drugs on immune function, and to determine whether any changes in immune function were related to recurrence. All indices were in the normal range before chemotherapy. The most marked and long-lasting effects of chemotherapy were on numbers of circulating T-cells and B-cells. Mean counts +/- one standard error (X 10(6)/ml) for T-cells before and 12 months after stopping chemotherapy were 1.537 +/- 0.118 and 0.874 +/- 0.120 (P less than 0.01), and for B-cells 0.345 +/- 0.060 and 0.207 +/- 0.030 (P less than 0.01). Functional indices of T-cell and B-cell competence were less compromised than values for cell counts and, in contrast, recovery occurred either during or within 3 months of stopping chemotherapy. This held for both T-cell function measured by delayed-type hypersensitivity (DTH) responsiveness to five recall antigens and mitogenic responsiveness to phytohemagglutinin, and for B-cell function measured by titration of blood group isohemagglutinins. After 4 years the 30 subjects were divided into groups according to whether there was recurrence of cancer (14) or no recurrence (16); the only index predictive of recurrence was depression of DTH to recall antigens. Thus it was found that cytotoxic chemotherapy with melphalan appears to cause long-lasting depression of cell counts but only short-lasting depression of functional indices of immunocompetence, and that levels of immunologic indices during chemotherapy are mostly nonpredictive of recurrence of cancer. The results prompt some caution in the use of adjuvant chemotherapy, at least with melphalan.

The effect of systemic adjuvant chemotherapy on local breast recurrence in node positive breast cancer patients treated by lumpectomy without radiation.

A randomised trial has previously been repeated in which 437 women with node positive breast cancer received either a 12-week chemohormonal regimen consisting of cyclophosphamide, methotrexate, fluorouracil, vincristine, prednisone, adriamycin and tamoxifen or 36 weeks of CMFVP. The present analysis concerns the local recurrence rates for the 122 lumpectomy patients who did not receive breast irradiation. The cumulative rate of local breast recurrence was greater in the 12-week than the 36-week group, P = 0.02. Similarly, in the lumpectomy patients, the cumulative rate of distant recurrence was greater in the 12-week than the 36-week group, P = 0.04. In conclusion, our results suggest that adjuvant chemotherapy impacts on local breast recurrence in a similar manner to other sites in Stage II breast cancer patients treated by lumpectomy without radiation. Despite the use of a conventional 36-week adjuvant chemotherapy regimen, the local breast recurrence rate was substantial.

Good outcome associated with a standardized treatment protocol using selective postoperative radiation in patients with clinical stage I adenocarcinoma of the endometrium.

In 1982, a treatment protocol was instituted for the management of patients with clinical stage I adenocarcinoma of the endometrium. All pertinent historical, operative, and pathologic findings were reviewed by a multidisciplinary committee and 384 patients were prospectively assigned to either high- or low-risk categories. Patients were excluded from the study if they had clinically apparent extrauterine disease, clear cell or serous histologies, or microscopic ovarian metastasis. Patients were considered high-risk if they had one or more of the following factors: grade 3 tumor differentiation, myometrial invasion > 50% of the total wall thickness, pathologic cervical involvement, or adenosquamous histology. Two-hundred twenty-seven (59%) low-risk patients were followed without further treatment after surgery, while pelvic radiation was recommended for 157 (41%) high-risk patients. The 5-year relapse-free survival rates in the low- and high-risk groups were 95 and 81%, respectively. There were no treatment-related deaths. Severe or life threatening chronic radiotherapy complications occurred in 6 (5%) patients. Multivariate Cox analysis identified the following significant prognostic factors: grade, myometrial invasion, cervix involvement, and age. This treatment protocol represents a safe and effective method of managing patients with carcinoma of the endometrium and spares the need for radiation therapy in the low-risk patient.