Radiotherapy of breast cancer.

Adjuvant radiotherapy is an essential component of the treatment of breast cancer. After conservative surgery for an infiltrating carcinoma, radiotherapy must be systematically performed, regardless of the characteristics of the disease, because it decreases the rate of local recurrence and by this way, specific mortality. A boost dose over the tumour bed is required if the patient is younger than 50 years-old. Partial breast irradiation could be routinely proposed as an alternative to whole breast irradiation, but only in selected and informed patients. For ductal carcinoma in situ, adjuvant radiotherapy must be also systematically performed after lumpectomy. After mastectomy, chest wall irradiation is required for pT3-T4 tumours and if there is an axillary nodal involvement, whatever the number of involved lymph nodes. After neoadjuvant chemotherapy and mastectomy, in case of pN0 disease, chest wall irradiation is recommended if there is a clinically or radiologically T3-T4 or node positive disease before chemotherapy. Axillary irradiation is recommended only if there is no axillary surgical dissection and a positive sentinel lymph node. Supra- and infraclavicular irradiation is advised in case of positive axillary nodes. Internal mammary irradiation must be discussed case by case, according to the benefit/risk ratio (cardiac toxicity). Hypofractionation regimens (42.5Gy in 16 fractions, or 41,6Gy en 13 or 40Gy en 15) are equivalent to conventional irradiation and must prescribe after tumorectomy in selected patients. Delineation of the breast, the chest wall and the nodal areas are based on clinical and radiological evaluations. 3D-conformal irradiation is the recommended technique, intensity-modulated radiotherapy must be proposed only in specific clinical situations. Respiratory gating could be useful to decrease the cardiac dose. Concomitant administration of chemotherapy in unadvised, but hormonal treatment could be start with or after radiotherapy.

The effects of 4 weeks normobaric hypoxia training on microvascular responses in the forearm flexor.

Intermittent exposure to hypoxia can lead to improved endurance performance. Currently, it is unclear whether peripheral adaptions play a role in improving oxygen delivery and utilization following both training and detraining. This study aimed to characterize skeletal muscle blood flow (mBF), oxygen consumption (mV̇O2), and perfusion adaptations to i) 4-weeks handgrip training in hypoxic and normoxic conditions, and ii) following 4-weeks detraining. Using a randomised crossover design, 9 males completed 30-min handgrip training four times a week in hypoxic (14% FiO2 ~ 3250m altitude) and normoxic conditions. mBF, mV̇O2 and perfusion were assessed pre, post 4-weeks training, and following 4-weeks detraining. Hierarchical linear modelling found that mV̇O2 increased at a significantly faster rate (58%) with hypoxic training (0.09 mlO2·min-1 · 100g-1 per week); perfusion increased at a significantly (69%) faster rate with hypoxic training (3.72 µM per week). mBF did not significantly change for the normoxic condition, but there was a significant increase of 0.38 ml· min-1 · 100ml-1 per week (95% CI: 0.35, 0.40) for the hypoxic condition. During 4-weeks detraining, mV̇O2 and perfusion significantly declined at similar rates for both conditions, whereas mBF decreased significantly faster following hypoxic training. Four weeks hypoxic training increases the delivery and utilisation of oxygen in the periphery.

[Radiotherapy of breast cancer]. / Radiothérapie du cancer du sein.

In breast cancer, radiotherapy is an essential component of the treatment. After conservative surgery for an infiltrating carcinoma, radiotherapy must be systematically performed, regardless of the characteristics of the disease, because it decreases the rate of local recurrence and by this way, specific mortality. Partial breast irradiation could not be proposed routinely but only in very selected and informed patients. For ductal carcinoma in situ, adjuvant radiotherapy must be also systematically performed after lumpectomy. After mastectomy, chest wall irradiation is required for pT3-T4 tumours and if there is an axillary nodal involvement, whatever the number of involved lymph nodes. After neo-adjuvant chemotherapy and mastectomy, in case of pN0 disease, chest wall irradiation is recommended if there is a clinically or radiologically T3-T4 or node positive disease before chemotherapy. Axillary irradiation is recommended only if there is no axillary surgical dissection and a positive sentinel lymph node. Supra and infra-clavicular irradiation is advised in case of positive axillary nodes. Internal mammary irradiation must be discussed case by case, according to the benefit/risk ratio (cardiac toxicity). Dose to the chest wall or the breast must be between 45-50Gy with a conventional fractionation. A boost dose over the tumour bed is required if the patient is younger than 60 years old. Hypofractionation (42.5 Gy in 16 fractions, or 41.6 Gy en 13 or 40 Gy en 15) is possible after tumorectomy and if a nodal irradiation is not mandatory. Delineation of the breast, the chest wall and the nodal areas are based on clinical and radiological evaluations. 3D-conformal irradiation is the recommended technique, intensity-modulated radiotherapy must be proposed only in case of specific clinical situations. Respiratory gating could be useful to decrease the cardiac dose. Concomitant administration of chemotherapy in unadvised, but hormonal treatment could be start with radiotherapy.

[Observance and results of concurrent chemoradiotherapy after induction chemotherapy by docetaxel, cisplatin and 5-fluoro-uracil for locally advanced head and neck cancers]. / Observance et résultats de la chimioradiothérapie concomitante après chimiothérapie d'induction par docétaxel, cisplatine et 5-fluoro-uracile pour les cancers de la tête et du cou localement évolués.

PURPOSE: Retrospectively evaluate the safety, feasibility and efficacy of concomitant chemoradiotherapy after induction chemotherapy by docetaxel, cisplatin and 5-fluoro-uracil for locally advanced head and neck cancers. PATIENTS AND METHODS: Patients' data from three radiotherapy centres in South of France, with locally advanced head and neck cancers, and treated between December 2007 and July 2013 by concomitant chemoradiotherapy, after induction chemotherapy by docetaxel, cisplatin and 5-fluoro-uracil, were analysed. Adverse effects were graduated according to CTCAE v3.0 criteria. Overall survival and disease-free survival were calculated according to Kaplan-Meier method. RESULTS: One hundred and sixty-eight patients, mostly oropharynx (38%) T4 (46%) N2 (54%) tumors, received, after induction chemotherapy by docetaxel, cisplatin and 5-fluoro-uracil, a concomitant chemoradiotherapy with platin or cetuximab, which delivered 66 to 70Gy. Grade 3-4 adverse effects were less frequent in the group of patients who received cisplatin (with or withour 5-fluoro-uracil) at 100mg/m(2) each 21 days compared to cetuximab (radiomucositis: 32.5% vs 61%, P=0.018; radioepithelitis: 13% vs 61 %, P<0.0001). Chemopotentiation was incomplete for 21% of patients without impacting survival. Two years overall survival and disease-free survival were respectively of 81% and 64%. Lymph nodes status and WHO status significantly influenced these survivals (overall survival 84% if N<3 vs 56% if N3, P=0.017 and 85 % if WHO status ≤ 1 vs 50% if WHO status>1, P=0.006; disease-free survival 66% if N<3 vs 47% if N3, P=0.046). CONCLUSION: The association of induction chemotherapy by docetaxel, cisplatin and 5-fluoro-uracil and concomitant chemoradiotherapy shows satisfying results with an acceptable toxicity. The terms of the chemopotentiation and its superiority to a single concomitant chemoradiotherapy treatment still remain to be clarified.

Flavor Ratio of Astrophysical Neutrinos above 35 TeV in IceCube.

A diffuse flux of astrophysical neutrinos above 100 TeV has been observed at the IceCube Neutrino Observatory. Here we extend this analysis to probe the astrophysical flux down to 35 TeV and analyze its flavor composition by classifying events as showers or tracks. Taking advantage of lower atmospheric backgrounds for showerlike events, we obtain a shower-biased sample containing 129 showers and 8 tracks collected in three years from 2010 to 2013. We demonstrate consistency with the (fe:fµ:fτ)⊕≈(1:1:1)⊕ flavor ratio at Earth commonly expected from the averaged oscillations of neutrinos produced by pion decay in distant astrophysical sources. Limits are placed on nonstandard flavor compositions that cannot be produced by averaged neutrino oscillations but could arise in exotic physics scenarios. A maximally tracklike composition of (0:1:0)⊕ is excluded at 3.3σ, and a purely showerlike composition of (1:0:0)⊕ is excluded at 2.3σ.

Development of a general analysis and unfolding scheme and its application to measure the energy spectrum of atmospheric neutrinos with IceCube: IceCube Collaboration.

We present the development and application of a generic analysis scheme for the measurement of neutrino spectra with the IceCube detector. This scheme is based on regularized unfolding, preceded by an event selection which uses a Minimum Redundancy Maximum Relevance algorithm to select the relevant variables and a random forest for the classification of events. The analysis has been developed using IceCube data from the 59-string configuration of the detector. 27,771 neutrino candidates were detected in 346 days of livetime. A rejection of 99.9999 % of the atmospheric muon background is achieved. The energy spectrum of the atmospheric neutrino flux is obtained using the TRUEE unfolding program. The unfolded spectrum of atmospheric muon neutrinos covers an energy range from 100 GeV to 1 PeV. Compared to the previous measurement using the detector in the 40-string configuration, the analysis presented here, extends the upper end of the atmospheric neutrino spectrum by more than a factor of two, reaching an energy region that has not been previously accessed by spectral measurements.

Observation of high-energy astrophysical neutrinos in three years of IceCube data.

A search for high-energy neutrinos interacting within the IceCube detector between 2010 and 2012 provided the first evidence for a high-energy neutrino flux of extraterrestrial origin. Results from an analysis using the same methods with a third year (2012-2013) of data from the complete IceCube detector are consistent with the previously reported astrophysical flux in the 100 TeV-PeV range at the level of 10(-8) GeV cm-2 s-1 sr-1 per flavor and reject a purely atmospheric explanation for the combined three-year data at 5.7σ. The data are consistent with expectations for equal fluxes of all three neutrino flavors and with isotropic arrival directions, suggesting either numerous or spatially extended sources. The three-year data set, with a live time of 988 days, contains a total of 37 neutrino candidate events with deposited energies ranging from 30 to 2000 TeV. The 2000-TeV event is the highest-energy neutrino interaction ever observed.

[Adenoid cystic carcinoma of the head and neck: a retrospective series of 169 cases]. / Carcinomes adénoïdes kystiques ORL : étude rétrospective multicentrique de 169 cas.

PURPOSE: Adenoid cystic carcinoma represents 1% of head and neck cancers. Adenoid cystic carcinomas are slow growing tumours with high potential for local recurrence. Treatment usually associates radiotherapy and surgery, but the role of radiotherapy remains unclear. We report a retrospective multicentric study of the management and prognostic factors of 169 adenoid cystic carcinomas of head and neck. PATIENTS AND METHODS: Between 1982 and 2010, 169 patients with adenoid cystic carcinoma of the head and neck were referred to the Cercle des oncologues radiothérapeutes du Sud departments of radiotherapy either for primary untreated tumour (n=135) or for a recurrence of previously treated tumour (n=34). The site of adenoid cystic carcinoma was: parotid gland (n=48, 28.4%), minor salivary gland (n=35, 20.7%), submandibular gland (n=22, 13%), sinus cavities (n=22, 13%), other (n=42, 24.9%). Tumour stages were: T1 (12.4%); T2 (14.2%); T3 (12.4%); T4 (41.4%) and Tx (19.5%). Lymph node involvement was 13% and distant metastasis 8.9%. For adenoid cystic carcinomas of the parotid gland, major nerve involvement was evaluated. Preferential site of metastasis was the lung (87.5%). Treatments were: surgery alone (n=27), surgery and adjuvant radiotherapy (n=89), surgery and adjuvant chemoradiotherapy (n=12), exclusive chemoradiotherapy (n=13), exclusive radiotherapy (n=14), other associations (n=5) and no treatment (n=7). Radiotherapy was delivered through photons (n=119), neutrons (n=6), both (n=4). Two patients had a brachytherapy boost. Median prescribed doses to T and N were respectively 65 Gy and 50 Gy for the 119 photons treated patients. RESULTS: Mean follow-up was 58 months (range 1-250 months). As of December 1, 2010, 83 patients were alive with no evolutive disease (49%), 35 alive and had recurred, 18 had uncontrolled evolutive disease, 28 had died of adenoid cystic carcinoma and 5 of intercurrent disease. Overall survival and disease free survival were respectively 72% and 72% at 5 years, 53% and 32% at 10 years; 5 and 10-year freedom from local recurrence were 81% and 52% respectively. Nerve involvement was found in 17/48 parotid gland adenoid cystic carcinomas. The Cox model including all patients, showed that surgery (P<0.001), surgical margins (P=0.015), nerve involvement (P=0.0079), length of radiotherapy (P=0.018), and tumour location (P=0.041) were associated with disease free survival. CONCLUSION: In this large series of adenoid cystic carcinoma of head and neck with a majority of T3-T4 tumours, 10-year survivals were achieved for 50% of patients. Radiotherapy did not impact survival.

Distinctive clinical and histologic features in cutaneous melanoma with copy number gains in 8q24.

Cutaneous melanoma may be quite heterogeneous in its clinical, histologic, and molecular features. Yet, the current classification of melanoma is limited to 4 main subtypes on the basis of clinical and histopathologic features and has shown limited impact on clinical management including prognostication and treatment. Advances in our understanding of the driving molecular pathways in melanoma and the importance of the mitogen-activated protein kinase pathway have shown that specific activating mutations in oncogenes may correlate with characteristic clinical and histologic features. We evaluated 40 melanoma cases with gains in MYC at 8q24, and we show that their characteristic features include aggressive clinical course, occurrence in nonchronically sun-damaged skin, amelanotic clinical and histopathologic appearance, a nodular or primary dermal growth pattern by histology, frequent epidermal consumption, and infrequent association with a precursor nevus. The v-raf murine sarcoma viral oncogene homolog B1 (BRAF) and neuroblastoma RAS viral oncogene homolog (NRAS) mutation status was also determined. The presence of these mutations was comparable to frequencies previously reported from nonchronically sun-damaged skin. However, the BRAF mutant cases did not show histopathologic features considered characteristic of BRAF mutant melanoma. Considering these distinct clinical and histopathologic features and the possible role as a theragnostic tool, it may be of value to consider 8q24 status in cutaneous melanoma in addition to the mutation status of BRAF in future studies integrating molecular findings into the classification system for cutaneous melanoma.

Limits on neutrino emission from gamma-ray bursts with the 40 string IceCube detector.

IceCube has become the first neutrino telescope with a sensitivity below the TeV neutrino flux predicted from gamma-ray bursts if gamma-ray bursts are responsible for the observed cosmic-ray flux above 10(18) eV. Two separate analyses using the half-complete IceCube detector, one a dedicated search for neutrinos from pγ interactions in the prompt phase of the gamma-ray burst fireball and the other a generic search for any neutrino emission from these sources over a wide range of energies and emission times, produced no evidence for neutrino emission, excluding prevailing models at 90% confidence.

[3D conformal radiation therapy and hormonal therapy for localized prostate cancer: is age a limiting factor?]. / La radiothérapie conformationnelle associée à l'hormonothérapie du cancer de prostate localisé: l'âge est-il un facteur limitant ?

No study on side effects had showed that conformal radiation therapy for prostate cancer is more harmful in patients older than 70 years to patients younger. The aim of this study was to evaluate acute and late toxicities of conformal radiotherapy, with high dose for localized prostate cancer in patients older than 70 years and compared to patients younger than 70 years. Between 1996 and 2009, 104 patients were treated with radiation therapy and hormonal therapy for localized cancer prostate. Median follow-up was 105 months (9-300). Acute (occurred at ≤ three months) and late side effects of 55 patients older than 70 years (median age: 75 [71-92]) were graded according to the CTCAE 3.0 criteria and compared to the younger population. Median dose to the prostate was 75.6 Gy (67-80) in both groups. There were no significant differences in acute and late side effects between age groups. For patients above 70 years, the incidence of grade II or higher acute and late side effects were respectively 27 and 22% for urologic symptoms and 13 and 16% for rectal symptoms. The frequency of grade III late symptoms was low and ranged between 0 and 6% for the evaluated symptoms, irrespective of age group. Older patients had a better biochemical recurrence-free survival than younger patients (86 versus 77% at four years, P=ns). High dose 3D conformal radiotherapy for localized prostate cancer was well tolerated in patients older than 70 years. Age is not a limiting factor for conformal radiation therapy and hormonotherapy for older patients.

[Postoperative radiotherapy of uterine sarcoma: a multicentric retrospective study]. / Radiothérapie postopératoire dans les sarcomes utérins: étude rétrospective multicentrique.

PURPOSE: Surgery is the treatment of choice for localized uterine sarcomas. We conducted a retrospective study to define prognostic factors. PATIENTS AND METHODS: We studied 111 cases of patients treated by adjuvant radiotherapy for uterine sarcoma in seven French centers. The median decline was 31 months. We conducted a univariate analysis to identify factors correlated with local recurrence. The statistically significant factors were studied in multivariate analysis by Cox model. RESULTS: The median dose of external beam radiotherapy was 45 Gy. Forty-three percent of patients had vaginal vault brachytherapy and 21 % chemotherapy. Only 6.3 % of patients had complications of acute grade III and 8.1 % of long-term sequelae of radiotherapy. The survival rate at 5 years was 74.6 %. They noted 12.6 % of isolated locoregional recurrences, against 29.7 % for distant recurrences, 80 % were pulmonary. Factors correlated with the risk of locoregional relapse were menopausal status (P = 0.045) and surgical margins suspicious or not healthy (P = 0.0095). The chemotherapy did not improve overall survival or disease free survival but the numbers were low. CONCLUSION: The postoperative radiotherapy provides good local control in this disease. Brachytherapy is sometimes done, but it does not improve local control. Chemotherapy is not a standard localized stage but the rate of metastatic recurrence calls for the development of strategies involving systemic treatment with radiotherapy.

[Evaluation of immediate breast reconstruction and radiotherapy: factors associated with complications]. / Reconstruction mammaire immédiate après mastectomie suivie de radiothérapie: facteurs de risque de complications.

OBJECTIVES: To determine prospectively the factors associated with reconstruction failure (i.e. requiring expander removal) and capsular contracture in patients undergoing mastectomy and immediate two-stage breast reconstruction with a tissue expander and implant, and radiotherapy for breast cancer. This is a multi-institutional prospective nonrandomized trial. PATIENTS AND METHODS: Between 2/1998 and 9/2006, we prospectively evaluated 141 consecutive patients who received 141 implants after mastectomy and underwent chest wall radiotherapy (46 to 50 Gy in 23 to 25 fractions). Patients were evaluated after 24 to 36 months by two senior physicians (radiation oncologist and surgeon). RESULTS: Medical follow-up was 37 months. Baker 1 and 2 capsular contracture was observed in 67.5% of patients, Baker 3 and 4 in 32.5%. There were 32 reconstruction failures. In a univariate analysis, the following factors were associated with Baker 3 and 4 capsular contracture: surgeon, use of hormonotherapy and smoking, of which only one remained in the multivariate analysis: surgeon. In a univariate analysis, the following factors were associated with reconstruction failure: tumor size T3 or T4, smoking, pN+ axilla. Three factors remained associated with reconstruction failure in a multiple logistic regression: large tumors T3/T4, smoking and pN+ axilla. CONCLUSIONS: Mastectomy, radiotherapy and immediate breast reconstruction with a tissue expander and implant should be considered when breast conserving surgery has been denied. Adequate patients can be easily selected by using three factors of favourable outcome.

Limits on a muon flux from neutralino annihilations in the sun with the IceCube 22-string detector.

A search for muon neutrinos from neutralino annihilations in the Sun has been performed with the IceCube 22-string neutrino detector using data collected in 104.3 days of live time in 2007. No excess over the expected atmospheric background has been observed. Upper limits have been obtained on the annihilation rate of captured neutralinos in the Sun and converted to limits on the weakly interacting massive particle (WIMP) proton cross sections for WIMP masses in the range 250-5000 GeV. These results are the most stringent limits to date on neutralino annihilation in the Sun.

Extending the search for neutrino point sources with IceCube above the horizon.

Point source searches with the IceCube neutrino telescope have been restricted to one hemisphere, due to the exclusive selection of upward going events as a way of rejecting the atmospheric muon background. We show that the region above the horizon can be included by suppressing the background through energy-sensitive cuts. This improves the sensitivity above PeV energies, previously not accessible for declinations of more than a few degrees below the horizon due to the absorption of neutrinos in Earth. We present results based on data collected with 22 strings of IceCube, extending its field of view and energy reach for point source searches. No significant excess above the atmospheric background is observed in a sky scan and in tests of source candidates. Upper limits are reported, which for the first time cover point sources in the southern sky up to EeV energies.

[Ductal carcinoma in situ: role of the boost]. / Radiothérapie des carcinomes canalaires in situ: impact du complément d'irradiation du lit tumoral.

Ductal carcinoma in situ is defined as breast cancer confined to the ducts of the breast without evidence of penetration of the basement membrane. Local treatment quality represents one of the most prognostic factors as half of recurrences are invasive diseases. The main goal of adjuvant radiotherapy after conservative surgery is to decrease local recurrences and to permit breast conservation with low treatment-induced sequelae. Several randomized trials have established the impact of 50 Gy to the whole breast in terms of local control. Nevertheless, no randomized trial is still available concerning the role of the boost in this disease. In this review, we present updated results of the literature and we detail the French multicentric randomized trial evaluating the impact of a 16 Gy boost after 50 Gy delivered to the whole breast in 25 fractions and 33 days. This protocol will start inclusions in October 2008.

Limits on the high-energy gamma and neutrino fluxes from the SGR 1806-20 giant flare of 27 December 2004 with the AMANDA-II detector.

On 27 December 2004, a giant gamma flare from the Soft Gamma-Ray Repeater 1806-20 saturated many satellite gamma-ray detectors, being the brightest transient event ever observed in the Galaxy. AMANDA-II was used to search for down-going muons indicative of high-energy gammas and/or neutrinos from this object. The data revealed no significant signal, so upper limits (at 90% C.L.) on the normalization constant were set: 0.05(0.5) TeV-1 m;{-2} s;{-1} for gamma=-1.47 (-2) in the gamma flux and 0.4(6.1) TeV-1 m;{-2} s;{-1} for gamma=-1.47 (-2) in the high-energy neutrino flux.

Constraints on cosmic neutrino fluxes from the Antarctic Impulsive Transient Antenna experiment.

We report new limits on cosmic neutrino fluxes from the test flight of the Antarctic Impulsive Transient Antenna (ANITA) experiment, which completed an 18.4 day flight of a prototype long-duration balloon payload, called ANITA-lite, in early 2004. We search for impulsive events that could be associated with ultrahigh energy neutrino interactions in the ice and derive limits that constrain several models for ultrahigh energy neutrino fluxes and rule out the long-standing -burst model.

[Radiosurgery and brain radio-induced carcinogenesis: update]. / Radiochirurgie et carcinogenèse radio-induite cérébrale. Le point actuel.

The use of radiosurgery Gamma-knife for many benign tumors and diseases has increased significantly over the last two decades. The long-term potential carcinogenic risk has not been evaluated until recently. The definition of radio-induced tumors was based on Cahan's criteria: it must occur in the previously irradiated field, with a sufficiently long interval from irradiation, it must be pathologically different from the primary tumor, not be present at time of irradiation and no genetic predisposition for second tumor. The brain is one of most sensitive tIssues and no minimal dose has been established. Even doses as low as 1 Gy have been associated with second tumor formation and relative risk between 1.57 and 8.75. This relative risk increases to 18.4 for an interval time between 20 and 25 Years. Many publications emphaze the risks after larger-field, fractionated radiotherapy with low non-cell-killing dose delivered to central nervous system. Furthermore, therapeutic radiation doses for benign tumors associated with a long life (parasellar tumors, meningioma) were implicated in carcinogenesis. Incidence of radiation-associated tumors is linked to different factors such as age and individual genetic susceptibility. At this time and to our knowledge, 3 radiation-associated gliomas and 5 malignant acoustic neurinomas have been reported in the literature. Moreover, these second tumors met some but not all Cahan criteria. We also report 2 cases from our radiosurgical experience and discuss these points. Long time follow-up is needed to observe the crude incidence of radiation-induced tumors at 5 to 30 Years. The relative risk is estimated less than 1 and must be announced to each patient before the radiosurgical procedure and counterbalanced wit the 1% annual risk of mortality from bleeding of untreated MAV or the 1% mortality rate of benign tumors after surgery alone.

The upper temperature of life--where do we draw the line?

A new archaeal isolate has been reported that is capable of growing at up to 121 degrees C. The hyperthermophile, dubbed strain 121, grows chemoautotrophically using formate as an electron donor and FeIII as an electron acceptor and is closely related to members of the archaeal genera Pyrodictium and Pyrobaculum. Although the reported maximum growth temperature of strain 121 is 8 degrees C higher than the previous record holder (Pyrolobus fumarii; Tmax = 113 degrees C), the two organisms have virtually the same optimal growth temperatures.